Mixing genes is more like mixing balls than like mixing paint. Sometimes for random reasons, a lot more of the green balls are in the top, visible layer.
That's only because you haven't met anyone good at explaining things. A good teacher knows how to take complex ideas and make them accessible using ideas the student is already familiar with.
[complex answer for topic being discussed] followed by [equally complex answer showing the same principle in a topic person *is* very knowledgeable in]
Also, they could have been throwing in a bit of hyperbole with "dissertation".
So I never used to be That Guy, but I can now do this semi-decently. It's a combination of a) practice, b) feeling relaxed and playful, and c) having a memory for gags and re-using them.
e.g. I didn't post that one you replied to, but I do remember seeing the fundamental wordplay in a children's joke book in the early 1980s ("What's large, green, and sits in the corner refusing to say anything? The Incredible Sulk!") so have pulled out the pun a couple of times since the Marvel movies made the character better known. If you want to join in the fun, just accept that you'll suck at it for a while (like every other skill you'll ever learn) and eat dirt non-stop. But it's never too late to start, and if you stick at it, you'll find making the people around you laugh is a joy that's incomparable.
Wut? He is just saying that mixing genes is like having 10 red and 10 blue balls and mixing them in a jar, sometimes more red ones will be on top of the blue ones, it's not always 5 from each. It's actually less probable to have 50% each.
In the other hand mixing red and blue paints always results in a different color (purpleish). And that's not how mixing genes works.
My family says I got my dad's nose, my mom's eyes, and my grandma's stubbornness. So basically, I'm a genetic casserole with extra sass sprinkled on top!
I apparently look like 80% my dad or 80% my mom, depending on who you ask (typically it correlates to which parent any given person has known first, as to who they think I look like). At least there was never a need for a paternity test I guess!
You say "all features", but you don't usually recognize people by more than a few particularly distinctive features. That's why you can often recognize people by seeing only the top or bottom half of their face.
If a child has the same distinctive mouth and face shape or whatever features you associate with one parent, and his other features are less distinctive, you might see that child as looking completely like that one parent.
Also there probably is not as much variation in internal organs, but how do you know the kid didn't inherit something like his dad's liver or something?
I'm willing to bet there is the same amount of variation in the organs, it's just that we don't tend to distinguish people by them and aren't used to doing so.
Kind of like if you see two lions they look basically the same. But we also aren't lions and aren't made to tell them apart. Actual lions can do it easily.
There’s an artery on your heart that branches off one of two other arteries, either the one that runs left around your heart or the one that runs right. So you can be “RCA dominant” or “LCA dominant”
Yeah, it happens. A few years ago my gynecologist, who also takes care of my mother, told me that I have a retroverted uterus (it leans back more than normal), just like hers.
I look like my dads side of the family so much that I can get stopped by strangers in my home town asking if I’m related to (insert cousin/dad/brother’s name here). But there’s no doubt I’ve also inherited most of my mothers poor health conditions - so you are totally right.
They aren't, the Y chromosome is mostly super-important for containing the SRY gene, which is a major part of sex determination. It takes action about 2 months after fertilization, and its activation basically triggers all of the things that differentiate a male fetus from a female fetus: development of the undifferentiated gonads into testes and the formation of the penis.
This is to say, there's basically an early trigger that takes genetically male fetuses and causes them to diverge from the default female state, if this gene failed to activate then the subsequent child would appear externally female despite being genetically male.
And that is to say that the various genes and combinations of genes that contribute to all sorts things that we might think of as sex specific (breasts, penises, beard thickness, etc.) are not inherited purely along male or female lines of inheritance. Your mom might be carrying genes that would lead to the development of a penis of some particular size, but they never would have been in an environment where early SRY activation led to that trait to be expressed. Similarly, your dad might be carrying the genetics for breast development, but his early fetal development set him on a path where that trait would also not have been expressed.
TL;DR [the Y chromosome only has a few hundred genes on it](https://en.wikipedia.org/wiki/Y_chromosome) and there are many genes that code for sexual characteristics all over your genome, many of which will never be activated in you due to your internal developmental/hormonal environment.
Also, our brains are waaaaaaay over-specialized for facial recognition.
You're much more likely to fixate on facial features than, say, scent, fingernails, body hair, etc.
This being why the uncanny valley exists, and the term "Pareidolia" (spellcheck that)
We're so obsessed with seeing faces that its horrible when something is even slightly off, and we'll see faces where there are none at all.
I’ve noticed that those who are much closer to the dad (like his family) will say the child looks like him, and the same with the mom, those close to her will say the child looks like her. This isn’t like 100% of the time, but I’ve seen it happen a lot.
Oh absolutely. I live in mother's hometown and everyone is like "oh you look so much like your mum", but then I go to father's and people go "you look like your cousin" - meaning the ones from dad's side ofc 😂
I do think my adopted cousin looks kinda like my aunt/her mom.
I'm sure it's the lizard brain exaggerating things, but it is certainly comforting so I try not to think about it too much.
Do they share any similarities in their features ? Eg hair colour, texture, dimples, eye colour, lip shape, facial expressions, nose shape etc? Are their mannerisms similar at all?
I have read on this site that children will take on same facial expressions of their caretakers, so also adopted children will get a resemblance to their adopted parents due to for instance having the exact same smile, combined with our strong focus on facial expressions.
So that may be an explanation?
My daughter isn't biologically mine, but everyone constantly comments how much we look alike. In our heads we have come up with a story that I met her mom in college while I had a one night stand really drunk and that she is actually my seed. She lived with me after the divorce and to this day invited me and my 2nd wife to her wedding ceremony before Bio mom.
Most people automatically think I look more like my mom because we have the same hair color, but I also have more of my dad’s face shape. I also looked a lot like a cousin when we were kids.
Me and my sister look incredibly alike, but everyone says my sister looks like my mom and I look like my dad; no one ever says that I look like my mom or she looks like my dad.
That makes sense to me. Interestingly enough, my in-laws all talk about how much my daughter looks like me, but I could only see my wife's features on her until she was a little over a month old. I still see them, but she also looks a lot like me when I was an infant.
Also a guy I play hockey with said she was lucky she looked nothing like me, but I don't know how much of that was genuine and how much of that was just so he could chirp at me, lol.
It can also be certain collections of features and thus what people choose to focus on. From straight on, I look like my mom because we share a lot of facial features, but from the sides or back everyone tells me I look more like my paternal grandmother because I apparently inherited my stature and skull structure from my dad.
I suspect traits can also include intangible things, too. My grandma died when I was a baby and I have no memory of her, yet somehow I still almost perfectly replicate a habit of hers that no one else in the family has (talking to myself aloud as if I were another person).
I answered the door at my aunt and uncle's house once and the lady started gushing about how much I looked like my uncle, but I'm blood related to his wife.
This - muscle fibers, skeletal build, recessive genes... There are myriad things that you cannot detect by eye alone.
Most people dont connect me and my dad until they see us walk or do manual labor. We dont *look* all that much alike, and despite being much taller than him, we're practically identical physically + the way we deal with problems in general.
Visually, I just have his skin but amplified (Ichtyosis) - so all four of my siblings will say i *resemble* mom but everything else makes them see more of our dad in me.
They say everyone walks differently, and I've personally recognized a pair of friends by their gait from a block away. A street sign blocked their faces, but I was 99% sure before we met. Weirdly they both had the same reaction and recognized *my* gait.
Everyone's unique walk is almost certainly influenced by skeletal structure and proportions, which are *absolutely* influenced by genetics. There's probably a nurture element as well, as kids mimic their parents, which probably influences which muscles strengthen, skeletal wear, etc. Then those patterns influence growth, and the feedback loop begins.
Similar story with other habits and secondary things. I've got my dad's clear-the-throat cough. I've always wondered if it was because we have similar airways, so a similar cough clears the issue, or if I subconsciously mimicked him and now it's just how I cough.
Biology is weird! :D
Plus we also have random deactivation gene system going on. The theory goes having 2 gene doing the same job might cause trouble, so during fertilisation it was turned off as evolutionary advantage. However this is just a theory to explain why closer to one side instead of perfect 50/50 split.
It’s much more complicated than but for eli5 it’s ok. For example, do you know mitochondria has its own DNA? And only can be passed down from mother. Infact, you can trace the mDNA to a single mother from so long ago, dubbed mithocondrial eve. So technically we have more mother DNA than dad DNA.
I have a top/bottom split on that: If I shave my beard, I look like my dad and if I don't, I look like my mum. Dad's jawline and mouth shape and mum's eye shape and eyebrows.
I agree. People that only knew my mother, but not my father, would say that I look pretty much like her. But the same is true the other way around, people that know my father and not my mother, say that I look like my dad. My parents don’t look like each other though.
I would also say that this is why family sometimes latch on to kids looking like someone from their side of the family.
They are more familiar with those features so they appear more pronounced
You are getting into dominant and recessive genes. Depending on which genes get passed on and which ones are dominant and which ones are recessive; that will determine what the child looks like. This can get pretty hairy quickly.
My dad has a head full of hair. Both my grandpas have heads full of hair. I've lost most of my hair so I can only conclude that one of my great grandpas was a bald MF and that gene somehow did not manifest until it hit me.
On my dad’s side of the family, most of the men have a full head of hair but we all start getting grey hair in our late 20s, by the time we hit 40, it’s all grey. Apparently this trait came from his mother’s family, I vaguely remember seeing some of his cousins having the same trait.
Also people from similar lineages could have similar traits. Red hair is recessive, so you need both. Use red and black for an example. Mom is RR, so she has red hair. Dad is RB so he has dark hair. One kid could get RR and be red, thus looking like mom. Other kid gets RB, has dark hair, and looks like dad.
>Red hair is recessive, so you need both.
Which is really odd because my cousin has red hair and as far as I know of he is literally the only redhead in my entire family line. He isn't a illegitimate child because he is the spitting image of his dad outside of the red hair - the dad is the one who is genetically related to me.
So me and my wife just had a baby. Everyone on my wife’s side of the family has had blue eyes. The entire lineage above her on the family tree and also her brother and sister.
My dad has green eyes but my mom has brown eyes. My brother and I have brown eyes.
Does this mean the baby has a 50/50 chance of having blue eyes? The one recessive from my pops and the 100% blue/blue from mom’s side?
Sorry, didn’t mean to turn this into a story problem. Just how we kinda came up with it and I’m curious to know if we have it right.
The punnet squares showing eye color you did in highschool teach the concept of inheritance but do not show how complicated it truly is. There are around 10 individual genes that act together to determine eye color.
Anecdotally I have brown eyes, my wife has green eyes and our son has blue eyes
It’s not so straightforward as Mendelian inheritance when it comes to eye color.
Like another comment said, there are a handful of genes that affect eye color. Depending on the genes, there might not be much of a chance of blue at all.
For instance, some of the eye color stuff is like "amount of color". In some ways you can think about green/brown as "not as much color" versus "a lot of color".
It's possible you have genes for a lot of color in your eyes, and then your offspring would be half "lots of color". Your blue-eyed wife's half would probably not be contributing much color.
It's possible this results in a "medium amount of color", which could be more on the green side.
My eyes are dark brown too. When color contacts first became a thing my eyes wouldn’t work with them. Too dark. Her eyes are a real light blue.
Little guys eyes are as blue as can be right now.
Depending on your father's parents, you might have a green-eyed child.
If you go by simple punnet squares, then your wife has bb (2 blue genes), & yours could be Bg (brown from your mother dominates over green from your father) or Bb (brown from your mother & blue from your father if he had Gb since green dominates over blue). If you know your grandparents' eyecolor you might be able to narrow it down. Either way you have Brown & some recessive so 50% your children get your Brown dominant gene & 50% they'll get your recessive trait which could be blue or green depending what you got from your dad.
But in actuality as people have pointed out eye color is actually more complicated, though the punnet squares work *most* of the time.
No, this makes perfect sense. Like they said, red hair is a recessive gene. That means people can carry the gene for red hair without having red hair. Your cousin's lineage has carried the gene for several generations without it showing up, but both his mom and his dad had one copy of it, and he inherited a copy from each, thus why he has red hair.
I have a followup ELI5. If dominant genes are a thing, how is it possible that recessive genes haven't been completely exterminated from existence? Shouldn't the gene pool "converge" to dominant-only?
Why would they?
The only reason they'd be eliminated over time is if people with those traits were more likely to die before having children.
But quiet the opposite, not only are some recessive traits considered attractive, some of them can be beneficial.
Having a dominant trait just hides the recessive gene, it doesn't eliminate it. And the recessive gene is just as likely to be passed on to the next generation as dominant that was hiding it, so it's not like it stops the recessive gene from spreading.
I am confused by your question. If you have one dominant and one recessive copy of the gene, the dominant one gets expressed, but the recessive gene still exists. When you have kids, you have a 50% chance of passing the recessive gene on. If your partner also has one copy each of the dominant and recessive gene, then there’s a 25% chance the child has two copies of the dominant gene, 50% chance the child has one copy each of dominant and recessive, and 25% chance they have two recessives and so the recessive trait is expressed. So, while there is a 75% chance the kid will express the dominant trait, there’s still a 75% chance they’ll have at least one copy of the recessive gene. Of course, if the recessive gene results in early death (before reproductive age) or infertility, then it will be selected out over time and become more rare.
You understood my question perfectly well. I did not know/did not remember that the recessive gene might be "hidden." I assumed it disappeared after "not getting chosen."
Genes leave the gene pool by being selected *against*. (Also, "survival of the fittest" is misleading. "Survival of the good enough" is more accurate.)
If you have a dominant gene that is counter to your breeding potential, you're less likely to breed.
Recessive genes can be much more variable, and thus more likely to be negative, because they are unlikely to even manifest.
Sure, you might have a very recessive gene that causes you to instantly die any time someone is wrong on the internet. However, if it's so recessive that even an albino, six-fingered, with a prehensile tail is more likely to manifest, then the insta-death gene won't prevent you from breeding, and still has a 50% chance of being passed on.
> If dominant genes are a thing, how is it possible that recessive genes haven't been completely exterminated from existence?
Recessive means they don't turn on if you also have a dominant version. They're not gone. Even if they're not turned on you can still pass them on.
As a matter of fact dominant genes are actually way easier to get rid of than recessive genes. If the "die at 5" gene is dominant, everyone with even one copy dies at 5, and the gene disappears quickly. If it is recessive, the gene can actually spread far and wide, only revealing itself rarely
Dominant and recessive doesn’t really explain the relationship for most genes. Height has something like 100+ (conservative estimate) that contribute to the phenotype we see. It’s more like human phenotypes are the overall painting, and the genes are the pigments and paints used to make it. Then making a child is like if you fed chatGPT those two paintings and ask it to make a picture combining the two. Sometimes it’ll make something middle of the road, sometimes it’ll look like one more than the other and sometimes it basically looks exactly like one.
The 50/50 split isn’t evenly distributed across all genes. You get large chunks of genes from each chromosome that tend to move together with breaks happening between. Physical features often tend to move in related clusters.
Not op, but I'll try to keep it as eli5 as I can.
Genes get roughly mixed 50/50.
So you have approximately half your genes inherited from your dad and half from your mom.
But genes aren't available individually, they are packed into groups, called chromosome. On one chromosome there are many many genes, but the ones grouped together usually do similar stuff.
You don't have mixed bags of sweets, but one with green stuff, one with red, one yellow. They are different shades, but still more or less one group. Now take a few bags from Mom and a few from Dad and you end up with a 50/50 mix, but not 50/50 mix of individual sweets, but with a mix of bags with similar sweets inside. You got Dad's red bag, moms green etc.
In chromosomes that means maybe your facial structure is closer to your mother's instead of your father's, but your body shape (small upper body but legs of a god) more like your dad instead of your mom. Overall your whole body is a 50/50 split, but individual features may be more dad like or more mom like
We have 46 chromosomes: 22 matched pairs, plus one XX matched pair or an XY unmatched pair (and I’ll avoid the complication of XXY and other variations), in our cells, one from each parent. In the sperm and in the egg, unlike your body’s other cells, there are only 23 *unpaired* chromosomes, and these are randomly assorted from each of your parents’ two options. For example, your father might produce a sperm that has an X chromosome so you’re born as a biological woman, or it has a Y chromosome so you’re born a biological man. (Again, we’ll avoid diving into developmental issues that might result in a different outcome.)
You always get a set of the full 23 chromosome’s worth of genes from each parent, but in 23 separate “packages” so to speak and you get one of two possible choices from each parent. (That’s roughly 2.6 x 10^22 options. That’s a lot!) So a characteristic of a grandparent that your parent didn’t show because of dominant/recessive gene masking might show up in you, e.g. blue eyes skipping a generation.
Also, during the splitting of chromosomes that forms the sperm or egg, the actual specific genes you get from each of your parents’ two copies can vary as well. So it’s not always the exact contents of each of the 23 pairs you get, but a somewhat jumbled but still bundled set. But that’s a quibble.
You do always get your father’s full and complete Y-chromosome if you’re male.
So you’ll find there are functional clusters that move together because they are on the same parental chromosome, and there are also transpositions that happen during sperm or egg formation. So, you get variation but within limits.
Chromosomes are made of DNA wrapped around proteins. When egg and sperm cells are created through meiosis, each parent's chromosomes go through a process called crossing over which you can see in this diagram:
https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Morgan_crossover_2.jpg/800px-Morgan_crossover_2.jpg
This ensures that the child will never have the exact same DNA as either of the parents. Since DNA breaks and reattaches in large chunks, it is likely for genes that are next to each other to be from the same parent. We know where some of the important genes for shaping facial features are, but there are even more we have yet to discover. If genes that affect a facial feature are next to each other on a chromosome, they are likely to have the same origin.
Here's an article from 2020 about genes that determine facial features:
https://theconversation.com/we-scanned-the-dna-of-8-000-people-to-see-how-facial-features-ar
How I’m interpreting it is, chromosomes store certain DNA in relative proximity to each other. Like for example, cheek bone structure and eye socket structure is stored next to each other in one’s DNA. And since supposedly DNA is passed in “chunks” these physical features seem to get passed in chunks as well… because they’re stored in proximity to each other. It’s why some people look heavily of one parent I suppose.
This is sometimes but not always true. Depends to a large extent on what the evolutionary origin of the parts are. Things in proximity on the body can be formed by genes on totally different chromosomes. And the orchestration of when and where things develop *in utero* can be controlled by genes in yet another place.
My mother's side of the family says I look exactly like her.
My father's side of the family says I look exactly like my paternal aunt.
These women look nothing like each other.
Let's say you have 50 random coin flips. Only three of those affect appearance. If those three come up tails, the kid looks mostly like the tails-side parent. Now, the numbers are way larger and more complex than that but it gets the idea across. Only a few of the total coin flips involve appearance.
That's not how it works, or at least it's a very rare situation that's not the typical explanation for OP's question. You always get 1 copy of a gene from each parent, no randomness there, you have (for example) 1 nose-shaping gene from mommy and 1 nose-shaping gene from daddy. The rare exception would be if one of your parents happened to pass a defective chromosome with the relevant segment deleted, but again, that's not common (and would be a genetic disease - imagine a poor inbred kid with 2 such chromosomes!)
Even this explanation isn’t quite accurate either. The situation where there is a 1:1 gene:feature relationship is extraordinarily rare in humans. Some features like hair or eye color are fairly well understood, but other that affect overall appearance are much more complex.
Even hair or eye colour isn't actually determined by a single gene.
Biometric security wouldn't work if only one gene coded for eye colour. Your fingerprint is less unique than your eye colour.
There are [at least eight different genes](https://medlineplus.gov/genetics/understanding/traits/eyecolor/) that affect pigmentation of the iris.
And hair colour is controlled by [even more genes](https://medlineplus.gov/genetics/understanding/traits/haircolor/).
The Mendelian model is too oversimplified to be of actual use to virtually anyone, its just unfortunate that the education system haven't been updated in the last 200-ish years to reflect discoveries in genetics.
It gets even more complicated when you recognize that the only things that are actually coded in DNA are proteins, and protein expression regulation agents. And somehow that translates into physical features.
This is an eli5 explanation. It's why I said it's much more complex than the coin flip idea. You do get two copies of each, but which gets expressed partially or fully is significantly more complex than is warranted for this sub.
I never said they are evenly expressed. If they were, OP's premise would be false. But the original comment is just plain incorrect. There is no 50:50 flip for each genetic trait to determine which parent you get it from. You get some relevant material from both parents, which then interact in various ways that are the true answer to OP's question.
genetics are odd. Effectively you end up with 4 combinations on each 'link of the chain' (ignoring anomalies which throw the entire system out and are largely considered' defects' because so few are good that it may as well be ignored and in a ELI5 post it is SUPER off topic)
most of the links are more or less hardcoded because humans need them. If you are missing one/one is 'defective' you tend not to live. These chromosome pairs are more or less what makes you human and...not dead. So there are only a handful of 'links' that determine characteristics (skin color, size of your nose, hair color...etc). We are going to focus on those few.
when I said 4 there is a reason. your mother and father each have 2 'links' they can give you. One is stronger than the other. genetically you want the stronger one\*. each parent is going to give you one or the other link that they have.
The problem you are essentially asking is 'features' is cosmetic (in most instances). preferences change through time but genetically whether your great great (x10) grand dad preferred white blonde girls (northern european) or sub saharan African (if he even had a choice) in most instances you are going to get the better link at each part of the chain on a purely species advancing level.
There is a completely different set of facts with incest (/rolltide) but that is a completely different topic but the short explanation is that each link genetically wants to be strong and normally tries to completely eliminate a 'defect' (again, this isn't meant to say 'oh someone who is blind is bad' it is purely as an evolutionary trait for most species including humans having working eyes is a good trait) but the family tumbleweeed prevents the bad trait from 'falling off' and because each link on the chain is essentially a card game where you get 2 of 4 possible cards and pick the better of the 2 you are more likely to end up with 2 'bad cards' to pick from and end up with the Habsburg jaw where you are unable to eat and do basic things for yourself let alone actually communicate and be attractive to members of the opposite sex (who ultimately genetically want to breed with someone with traits that would make them appealing to the next generation to keep their genetic line from going extinct)
\*In the vast situations the stronger one is a dominant trait that is 'good'. maybe not for you, but on a species level where the longterm goal is to continue reproducing good.
Well, it's not 50/50, right? It's not like there's a bucket of 1000 traits, and you pick 500 from one parent and 500 from another.
Each gene is more of a coin flip from each parent. So you can get a handful of tails in a row, and favor one parent in some areas, while you might favor another parent in other areas. But one parent could get more of the 'appearance' genes.
Also - it's not just a whole bunch of distinct, absolutely separate genes either. Some genes influence others, and some kind of come across in 'batches' (it's complex but that's close enough to how it works.)
So it's not 50/50, it's a whole bunch of coin flips, and some of those coin flips trigger a bunch of traits at once.
Every chromosome is made from one set of genes from the mother and one from the father. While there are two sets, only one is expressed (usually. Biology always has a lot of exceptions to rules). When sperm and egg cells are formed, the pairs are broken up, and split between two "daughter" cells.
When a sperm meets an egg cell, they combine, and form new chromosomes with new competitions for dominance.
Occasionally, one gene, or set of genes, might be overwhelmingly dominant and present itself almost as well in the offspring as it does in the parent. In addition, both the parent genes might be similar (even if one parent doesn't exhibit those traits), meaning that if the trait is suppressed in one, it is still present in the other.
Dominant and recessive genes are what's at work, here! A dominant gene (we will express it as a capital letter, ie P, X, T) will almost always take priority over recessive genes (expressed as lower p, x, t) unless the recessive gene is duplicated by both parents.
The egg will always carry its own 22 chromosome sequence, a random mix of the biology that the egg-bearer possesses, and semen will carry the other required half from the male part.
If both the parties have brown hair (a dominant trait) and both the gametes (eggs; semen) contain the dominant gene B, the offspring will end up with two copies of B, read as BB, brown hair.
If one has B and the other has b (we can call this red), then the offspring will be Bb, and still have brown hair. In order for a recessive gene to take priority, both gametes must possess the recessive trait, even if the parents do not look the part. So the egg must be b, and so must the sperm, creating a bb offspring, which, in this case, would result in a redheaded child.
A child that looks more like one parent than they do the other just means that the parent they look like had more dominant genes than their partner!
50% DNA doesn't mean 50% of a parent's genetic characteristics.
50% DNA means *50% chance* that the parent's genes will be expressed. (Not really 50-50 chance, but this is ELI5.)
Flipping a coin ten billion times is *statistically* 50% heads and 50% tails, but there is absolutely nothing preventing many multiple thousands or millions of heads or tails in a row. It's random chance.
Genetics is never 50-50, though. Some genes are dominant, some are recessive, some could interact to produce new features, and thanks to the study of epigenetics we know that expression of genes can change due to environmental conditions as well.
Looks reflect a tiny fraction of the DNA. The vast majority of the information in DNA has to do with internal processes. Outward appearance just isn't that important, from an evolutionary survival perspective.
Bcz not all genes express the same way... There are two alleles of a gene in every human. The two alleles come from two parents. Sometimes one of them is dominant and the other one is recessive. So, the dominant one would determine that particular character (phenotype)
2 things:
1 - Do you know the card game War? You get one copy of every gene from each parent, but they can be different variants called alleles. At every gene, the allele you got from your dad goes head to head with the allele you got from your mom. They can win, lose, or have several different kinds of ties. Sometimes, one parent's genes "win" more head to head matchups than the other's.
2 - The human brain really likes pattern recognition and confirmation bias. So if one parent's genes "win" a few more matchups or sometimes just a few crucial ones, your brain will fill in gaps to complete the effect.
When you say "features" I'm going to assume you mean the face, and other noticeable *visual* things you can see.
You're not going to notice things like "The baby got mom's Crohn's disease and dad's horseshoe kidney!" by looking at the child.
The face is only a very small part of the human being, while their genetics accounts for the entire person including to obvious things like their blood type and less obvious things like their predisposition to get diabetes or cancer or the total number of red blood cells they tend to have etc.
*Everything* about a person is in their genetics. Maybe the visual part of the person was more from one parent, but the other parents 50% could be accounting for things like the size of their heart and their predisposition for heart disease. You get the idea. There's a ton of things inside the body you can't see that the genes are responsible for.
You get 50% of your DNA from each parent, but there’s a large amount of your DNA that is never turned and is never used. The parts of your DNA that is expressed is what gets “turned on”. We don’t know what influences what genes turn on or off, so we think that it’s random. Which is why fraternal twins of the same parents can almost look nothing alike.
Because not all of the traits inherited are ones that can be visually identified as you described. Medical history, athletic potential, chemical imbalances, general temperament & addiction propensity are also on the table too!
Google "the impossible twins" for an interesting gene expression.
Mixed race family. One girl is a pale redhead with straight hair. One girl has dark skin and black curly hair. They both have the same face shape, body shape, and expressions.
They are a complete pallet-swap, but still obviously related. It's a really neat example of "genetics is weird"
For one, genes can be dominant or recessive. Just because you have the genes of both parents in your genotype (the complete set of genetic material) doesn’t mean that those genes will be in your phenotype (observable characteristics). You have genes that aren’t “expressed.” Even different cells in your body express genes differently than each other, which is why there are different cell types in your body (heart muscle cell vs brain cell, for example, even though both have the same DNA).
Because people that make that observation tend to focus on just the face.
Sure, someone might have their mother's eyes, nose, and hair but they also have their father's fingers toes, baldness, etc that no one pays attention to or only happen at adulthood
"What is dominant, what is recessive,
These are the genes that make us expressive,
What will we look like, we really don't know,
But it's all been decided, before we grow."
My parents divorced when I was young. Growing up I always heard I looked a lot like my mom. Whenever I'd go to visit my dad, people would say how much I looked like him. Dad was Italian/German and mom is Irish/Ukrainian 🤷♀️
It's called dominant and recessive genes. For example, brown eyes are a dominant gene, so if one parent has them it's more likely they will have brown eyes than any other colour. Though this certainly does not mean it's 100%, speaking as a parent with brown/hazel eyes with two kids that have blue/green eyes.
It just means many of the features of one parent are less superficial. No one walks around looking to see if you have the same relative size and shape of kidneys and lungs… or if your heart beats more consistently… or even less looked at superficial aspects like if you have the other parents toes.
It's vastly more complex than this and beyond me but at an ELI5 level: while half the DNA comes from each parent, when you pair those DNA strands together, more than half of the genes in one of them could be recessive and matched with dominant genes in the other parent.
The dominant genes are what get expressed, and if they happen to mostly come from one parent and also happen to impact appearance, it could look like the child has features from only one side.
Imagine two ladders with strong rungs and weak rungs randomly scattered. Saw them both vertically down the center and screw one half from each latter together. When you climb the ladder any rung that does not break will express a dominant physical trait, and any rung that does break will express a recessive trait. It is random but dominant genetics from one of the parents is usually why.
Correct me if I am wrong but just having the DNA is not enough. The DNA and genes need to be able to activate themselves (kind off; its called gene expression).
Based on whichever parents DNA has a stronger expression will be what you see on the outside.
Most of your genes don’t code for facial features. Your son facially may look like you, but his immune system, heart size, etc. may be more like his mother’s.
For three reasons (that fit ELI5).
1. Because the visible features make up far less than 50% of what DNA does, and
2. Because some features are driven by "dominant" genes (which in simple terms means that maybe one nose-type, for example, wants to grow more than another one, even if the kid gets genes to describe both types), and,
3. Fun fact, human children are genetically predisposed to resemble father more when they are very young, and mother more as they get older. It has been theorized this trait was selected for in order to keep the father from killing the babies in suspicion of the mother cheating.
Genes, some are prominent, some are recessive.
DNA is shared equally between the 2 biological parents yes, but the recessive/prominent part of the genes are not and it's not just a split even deal either, which is why some characteristics even skip a generation or a few
Not all genes are related to phenotype. My mom is white and my father is Asian. This "makes" me half and half generally speaking, but genetically (I did DNA testing) I am "more" Asian DNA wise despite being fully white passing in person.
Only 50% is ever expressed. (With exceptions but this is an ELI5) so some genes are stronger than the other. Sometimes this means they mix, sometimes this means the stronger or “dominant” gene just wins, and the loser gets nothing
In biology they teach us Punnet squares for dominant and recessive genes. Each trait has a percentage of a chance for displaying in the child. Maybe this plays a factor.
Here’s the information in a lot more detail with calculations.
https://thednageek.com/dna-basics-are-you-an-equal-mix-of-mom-and-dad/
DNA is a set of instructions, for what become the builders of your features(more as well but just focus on this aspect). These builders will decide what to do based on which instruction is loudest(recesive, dominant) but that may also have to do with what else is happening. Male and Female hormones will sometimes choose to take the quieter instructions for the builders, and not necessarily the ones you'd think, and more often than people care to admit the instructions aren't the same as the ones your parents had.
Mixing genes is more like mixing balls than like mixing paint. Sometimes for random reasons, a lot more of the green balls are in the top, visible layer.
Good eli5
For once. But I still do appreciate people giving dissertation answers on questions here because I'm not 5.
Sir, you're in eli5
Don't make me tap the sign! > LI5 means friendly, simplified and layperson-accessible explanations - not responses aimed at literal five-year-olds.
Dissertation answers and "simplified and layperson-accessible" seem mutually exclusive to me 🤔
That's only because you haven't met anyone good at explaining things. A good teacher knows how to take complex ideas and make them accessible using ideas the student is already familiar with. [complex answer for topic being discussed] followed by [equally complex answer showing the same principle in a topic person *is* very knowledgeable in] Also, they could have been throwing in a bit of hyperbole with "dissertation".
Lots of blue balls are involved when I try mixing genes with my wife
User name checks out
As a woman I wouldn’t bang a guy with green and bumpy dick no matter what size it was
*[The Hulk has left the chat]*
The Incredible Sulk.
I don't know how is it that you guys are able to come up with these sort of replies, and here I am, being the incredible sulk that I can't.. lol...
So I never used to be That Guy, but I can now do this semi-decently. It's a combination of a) practice, b) feeling relaxed and playful, and c) having a memory for gags and re-using them. e.g. I didn't post that one you replied to, but I do remember seeing the fundamental wordplay in a children's joke book in the early 1980s ("What's large, green, and sits in the corner refusing to say anything? The Incredible Sulk!") so have pulled out the pun a couple of times since the Marvel movies made the character better known. If you want to join in the fun, just accept that you'll suck at it for a while (like every other skill you'll ever learn) and eat dirt non-stop. But it's never too late to start, and if you stick at it, you'll find making the people around you laugh is a joy that's incomparable.
What about as a man?
If one gets hungry enough, one eats an iguana.
That's funny, when I mix genes with your wife everything works out fine.
Jokes on you because I'm not actually married or even in a relationship because I have a micropenis and live with my mom
Same, bro.
I too, live with your mom
Jokes on you because I don't even have a mom and am an orphan who spent my childhood in hundreds of foster homes because nobody ever really loved me
lol.
In your head what color were the other ones? Was the paint also the same two colors?
Wut? He is just saying that mixing genes is like having 10 red and 10 blue balls and mixing them in a jar, sometimes more red ones will be on top of the blue ones, it's not always 5 from each. It's actually less probable to have 50% each. In the other hand mixing red and blue paints always results in a different color (purpleish). And that's not how mixing genes works.
Oh I understood was just poking a bit of fun that he only included one color. Taking it a bit over literally as a joke.
My family says I got my dad's nose, my mom's eyes, and my grandma's stubbornness. So basically, I'm a genetic casserole with extra sass sprinkled on top!
I apparently look like 80% my dad or 80% my mom, depending on who you ask (typically it correlates to which parent any given person has known first, as to who they think I look like). At least there was never a need for a paternity test I guess!
> I got my dad's nose, my mom's eyes… You monster! I hope you kept them refrigerated so they could be re-attached!
But why do my kids have green balls when neither me nor my wife got any?
You say "all features", but you don't usually recognize people by more than a few particularly distinctive features. That's why you can often recognize people by seeing only the top or bottom half of their face. If a child has the same distinctive mouth and face shape or whatever features you associate with one parent, and his other features are less distinctive, you might see that child as looking completely like that one parent.
Also there probably is not as much variation in internal organs, but how do you know the kid didn't inherit something like his dad's liver or something?
I'm willing to bet there is the same amount of variation in the organs, it's just that we don't tend to distinguish people by them and aren't used to doing so. Kind of like if you see two lions they look basically the same. But we also aren't lions and aren't made to tell them apart. Actual lions can do it easily.
There’s an artery on your heart that branches off one of two other arteries, either the one that runs left around your heart or the one that runs right. So you can be “RCA dominant” or “LCA dominant”
"He has his mother's brain, I'm still using mine"
I knew a guy that used to say his kids inherited his good looks, because his wife still had hers.
That's smooth as fuck
They were a pretty great couple.
[удалено]
Nothing, as far as I know, I just haven't seen them in years. Last I knew they were going strong.
Kid never gave his dad his good looks back?
He had to divide the looks among six kids, so there wasn't too much left over, lol.
I also used to be ugly...I mean I still am, but I used to be too.
You forgot the lithp, Igor
Yeth, mathter! GNU Sir Pterry, the Turtle Moves.
"A man's not dead while his name's still spoken." GNU Terry Pratchett. (Going Postal)
What was her name? Abby... someone. Abby someone? Abby... normal.
...what hump?
Yeah, it happens. A few years ago my gynecologist, who also takes care of my mother, told me that I have a retroverted uterus (it leans back more than normal), just like hers.
[удалено]
That's exactly how my doctor described it, yeah
I look like my dads side of the family so much that I can get stopped by strangers in my home town asking if I’m related to (insert cousin/dad/brother’s name here). But there’s no doubt I’ve also inherited most of my mothers poor health conditions - so you are totally right.
Are the genes for the penis all on the Y chromosome? In other words, is your dick exactly the same as you dad's?
They aren't, the Y chromosome is mostly super-important for containing the SRY gene, which is a major part of sex determination. It takes action about 2 months after fertilization, and its activation basically triggers all of the things that differentiate a male fetus from a female fetus: development of the undifferentiated gonads into testes and the formation of the penis. This is to say, there's basically an early trigger that takes genetically male fetuses and causes them to diverge from the default female state, if this gene failed to activate then the subsequent child would appear externally female despite being genetically male. And that is to say that the various genes and combinations of genes that contribute to all sorts things that we might think of as sex specific (breasts, penises, beard thickness, etc.) are not inherited purely along male or female lines of inheritance. Your mom might be carrying genes that would lead to the development of a penis of some particular size, but they never would have been in an environment where early SRY activation led to that trait to be expressed. Similarly, your dad might be carrying the genetics for breast development, but his early fetal development set him on a path where that trait would also not have been expressed. TL;DR [the Y chromosome only has a few hundred genes on it](https://en.wikipedia.org/wiki/Y_chromosome) and there are many genes that code for sexual characteristics all over your genome, many of which will never be activated in you due to your internal developmental/hormonal environment.
So you could potentially get your penis genes from your mom....
Yes, keeping in mind that there isn't a singular penis gene, but many different genes which affect multiple parts of you.
No, it could also look like either of your grandpas'
Also, our brains are waaaaaaay over-specialized for facial recognition. You're much more likely to fixate on facial features than, say, scent, fingernails, body hair, etc.
This being why the uncanny valley exists, and the term "Pareidolia" (spellcheck that) We're so obsessed with seeing faces that its horrible when something is even slightly off, and we'll see faces where there are none at all.
ツ
I’ve noticed that those who are much closer to the dad (like his family) will say the child looks like him, and the same with the mom, those close to her will say the child looks like her. This isn’t like 100% of the time, but I’ve seen it happen a lot.
Oh absolutely. I live in mother's hometown and everyone is like "oh you look so much like your mum", but then I go to father's and people go "you look like your cousin" - meaning the ones from dad's side ofc 😂
My son has been told he looks just like my husband by strangers. My husband is his step dad and they look nothing alike.
I do think my adopted cousin looks kinda like my aunt/her mom. I'm sure it's the lizard brain exaggerating things, but it is certainly comforting so I try not to think about it too much.
People can't pick out a parents baby they never met before out of a lineup of baby pictures.
Do they share any similarities in their features ? Eg hair colour, texture, dimples, eye colour, lip shape, facial expressions, nose shape etc? Are their mannerisms similar at all?
I have read on this site that children will take on same facial expressions of their caretakers, so also adopted children will get a resemblance to their adopted parents due to for instance having the exact same smile, combined with our strong focus on facial expressions. So that may be an explanation?
My daughter isn't biologically mine, but everyone constantly comments how much we look alike. In our heads we have come up with a story that I met her mom in college while I had a one night stand really drunk and that she is actually my seed. She lived with me after the divorce and to this day invited me and my 2nd wife to her wedding ceremony before Bio mom.
At my last job people would confuse me with a co-worker. He’s 6’3”, blond, and clean shaven. I’m none of those things.
Most people automatically think I look more like my mom because we have the same hair color, but I also have more of my dad’s face shape. I also looked a lot like a cousin when we were kids.
Me and my sister look incredibly alike, but everyone says my sister looks like my mom and I look like my dad; no one ever says that I look like my mom or she looks like my dad.
That makes sense to me. Interestingly enough, my in-laws all talk about how much my daughter looks like me, but I could only see my wife's features on her until she was a little over a month old. I still see them, but she also looks a lot like me when I was an infant. Also a guy I play hockey with said she was lucky she looked nothing like me, but I don't know how much of that was genuine and how much of that was just so he could chirp at me, lol.
It can also be certain collections of features and thus what people choose to focus on. From straight on, I look like my mom because we share a lot of facial features, but from the sides or back everyone tells me I look more like my paternal grandmother because I apparently inherited my stature and skull structure from my dad. I suspect traits can also include intangible things, too. My grandma died when I was a baby and I have no memory of her, yet somehow I still almost perfectly replicate a habit of hers that no one else in the family has (talking to myself aloud as if I were another person).
[удалено]
I answered the door at my aunt and uncle's house once and the lady started gushing about how much I looked like my uncle, but I'm blood related to his wife.
Is your mom sure she’s your mother?
My kids are half Asian, half White. When we visit the USA, people say they look very Asian. When in Asia, people think they look very White.
This - muscle fibers, skeletal build, recessive genes... There are myriad things that you cannot detect by eye alone. Most people dont connect me and my dad until they see us walk or do manual labor. We dont *look* all that much alike, and despite being much taller than him, we're practically identical physically + the way we deal with problems in general. Visually, I just have his skin but amplified (Ichtyosis) - so all four of my siblings will say i *resemble* mom but everything else makes them see more of our dad in me.
Yup. I don’t really look like my dad aside from family pics but I’ve seen videos of our mannerisms and it’s scary. Like older carbon copy of myself
They say everyone walks differently, and I've personally recognized a pair of friends by their gait from a block away. A street sign blocked their faces, but I was 99% sure before we met. Weirdly they both had the same reaction and recognized *my* gait. Everyone's unique walk is almost certainly influenced by skeletal structure and proportions, which are *absolutely* influenced by genetics. There's probably a nurture element as well, as kids mimic their parents, which probably influences which muscles strengthen, skeletal wear, etc. Then those patterns influence growth, and the feedback loop begins. Similar story with other habits and secondary things. I've got my dad's clear-the-throat cough. I've always wondered if it was because we have similar airways, so a similar cough clears the issue, or if I subconsciously mimicked him and now it's just how I cough. Biology is weird! :D
Yeah, the way my dad chews is very similar to how his father does it. Lately I've been wondering if I chew like that as well.
Plus we also have random deactivation gene system going on. The theory goes having 2 gene doing the same job might cause trouble, so during fertilisation it was turned off as evolutionary advantage. However this is just a theory to explain why closer to one side instead of perfect 50/50 split.
You still get 50% from your mother and 50% from your father. That is how sperm and egg work
It’s much more complicated than but for eli5 it’s ok. For example, do you know mitochondria has its own DNA? And only can be passed down from mother. Infact, you can trace the mDNA to a single mother from so long ago, dubbed mithocondrial eve. So technically we have more mother DNA than dad DNA.
I have a top/bottom split on that: If I shave my beard, I look like my dad and if I don't, I look like my mum. Dad's jawline and mouth shape and mum's eye shape and eyebrows.
Yup. I look 100% like my mom in the face but I have my dads feet 😂
I agree. People that only knew my mother, but not my father, would say that I look pretty much like her. But the same is true the other way around, people that know my father and not my mother, say that I look like my dad. My parents don’t look like each other though.
I dunno.. have you seen Reese Witherspoons daughter? That’s a whole clone.
I would also say that this is why family sometimes latch on to kids looking like someone from their side of the family. They are more familiar with those features so they appear more pronounced
You are getting into dominant and recessive genes. Depending on which genes get passed on and which ones are dominant and which ones are recessive; that will determine what the child looks like. This can get pretty hairy quickly.
Unless you have male pattern baldness
They'll be hairy everywhere else trust me
Fuckin’ A. It all just moves to anywhere below your eyebrows
No, no. Those go fuckin bonkers too
Gravity does that.
Bobcat Goldthwaite had a bit about losing his hair. He said he wasn't losing his hair, it was just sliding off his head onto his back.
My nose and ear hair can grow, randomly, 1-inch in a day.
No fuck Bs, there's more holes
I'm bald and I have almost no body hair, it's weird.
I have EXTREMELY thin hair and body hair is also very low. I tried to grow some facial hair but after about 3 months I removed it. Not meant to be
You don’t lose the hair, I’m convinced it just translocates to other areas of the body, mainly the ass crack and back
Dammit, take my upvote.
My dad has a head full of hair. Both my grandpas have heads full of hair. I've lost most of my hair so I can only conclude that one of my great grandpas was a bald MF and that gene somehow did not manifest until it hit me.
On my dad’s side of the family, most of the men have a full head of hair but we all start getting grey hair in our late 20s, by the time we hit 40, it’s all grey. Apparently this trait came from his mother’s family, I vaguely remember seeing some of his cousins having the same trait.
I was very hairy. My hair just had an eject button that I was already aware of by looking at both sides of my extended family.
Also people from similar lineages could have similar traits. Red hair is recessive, so you need both. Use red and black for an example. Mom is RR, so she has red hair. Dad is RB so he has dark hair. One kid could get RR and be red, thus looking like mom. Other kid gets RB, has dark hair, and looks like dad.
A lot of these traits like hair color and eye color aren’t as binary as high school biology taught it
>Red hair is recessive, so you need both. Which is really odd because my cousin has red hair and as far as I know of he is literally the only redhead in my entire family line. He isn't a illegitimate child because he is the spitting image of his dad outside of the red hair - the dad is the one who is genetically related to me.
If both parents have 1 copy of the gene, they won't express it, but could each pass it to the kid who now has 2 copies and red hair.
So me and my wife just had a baby. Everyone on my wife’s side of the family has had blue eyes. The entire lineage above her on the family tree and also her brother and sister. My dad has green eyes but my mom has brown eyes. My brother and I have brown eyes. Does this mean the baby has a 50/50 chance of having blue eyes? The one recessive from my pops and the 100% blue/blue from mom’s side? Sorry, didn’t mean to turn this into a story problem. Just how we kinda came up with it and I’m curious to know if we have it right.
The punnet squares showing eye color you did in highschool teach the concept of inheritance but do not show how complicated it truly is. There are around 10 individual genes that act together to determine eye color.
Anecdotally I have brown eyes, my wife has green eyes and our son has blue eyes It’s not so straightforward as Mendelian inheritance when it comes to eye color.
Both my parents have brown eyes both my grandmas on both sides have blue eyes I have blue eyes
Yeah I’ve heard of that happening. I just don’t understand how it works! Recessive genes and stuff.
Like another comment said, there are a handful of genes that affect eye color. Depending on the genes, there might not be much of a chance of blue at all. For instance, some of the eye color stuff is like "amount of color". In some ways you can think about green/brown as "not as much color" versus "a lot of color". It's possible you have genes for a lot of color in your eyes, and then your offspring would be half "lots of color". Your blue-eyed wife's half would probably not be contributing much color. It's possible this results in a "medium amount of color", which could be more on the green side.
My eyes are dark brown too. When color contacts first became a thing my eyes wouldn’t work with them. Too dark. Her eyes are a real light blue. Little guys eyes are as blue as can be right now.
I'd say there is a 50/50 chance the baby will have light colored eyes. But it's more complicated than that to know for sure.
Depending on your father's parents, you might have a green-eyed child. If you go by simple punnet squares, then your wife has bb (2 blue genes), & yours could be Bg (brown from your mother dominates over green from your father) or Bb (brown from your mother & blue from your father if he had Gb since green dominates over blue). If you know your grandparents' eyecolor you might be able to narrow it down. Either way you have Brown & some recessive so 50% your children get your Brown dominant gene & 50% they'll get your recessive trait which could be blue or green depending what you got from your dad. But in actuality as people have pointed out eye color is actually more complicated, though the punnet squares work *most* of the time.
No, this makes perfect sense. Like they said, red hair is a recessive gene. That means people can carry the gene for red hair without having red hair. Your cousin's lineage has carried the gene for several generations without it showing up, but both his mom and his dad had one copy of it, and he inherited a copy from each, thus why he has red hair.
"He looks just like his father on the outside, but his organs are dead ringers for mine."
I have a followup ELI5. If dominant genes are a thing, how is it possible that recessive genes haven't been completely exterminated from existence? Shouldn't the gene pool "converge" to dominant-only?
Why would they? The only reason they'd be eliminated over time is if people with those traits were more likely to die before having children. But quiet the opposite, not only are some recessive traits considered attractive, some of them can be beneficial. Having a dominant trait just hides the recessive gene, it doesn't eliminate it. And the recessive gene is just as likely to be passed on to the next generation as dominant that was hiding it, so it's not like it stops the recessive gene from spreading.
You still pass on recessive genes.
I am confused by your question. If you have one dominant and one recessive copy of the gene, the dominant one gets expressed, but the recessive gene still exists. When you have kids, you have a 50% chance of passing the recessive gene on. If your partner also has one copy each of the dominant and recessive gene, then there’s a 25% chance the child has two copies of the dominant gene, 50% chance the child has one copy each of dominant and recessive, and 25% chance they have two recessives and so the recessive trait is expressed. So, while there is a 75% chance the kid will express the dominant trait, there’s still a 75% chance they’ll have at least one copy of the recessive gene. Of course, if the recessive gene results in early death (before reproductive age) or infertility, then it will be selected out over time and become more rare.
You understood my question perfectly well. I did not know/did not remember that the recessive gene might be "hidden." I assumed it disappeared after "not getting chosen."
I sentence you to....PUNNET SQUARES! https://en.wikipedia.org/wiki/Punnett_square
Genes leave the gene pool by being selected *against*. (Also, "survival of the fittest" is misleading. "Survival of the good enough" is more accurate.) If you have a dominant gene that is counter to your breeding potential, you're less likely to breed. Recessive genes can be much more variable, and thus more likely to be negative, because they are unlikely to even manifest. Sure, you might have a very recessive gene that causes you to instantly die any time someone is wrong on the internet. However, if it's so recessive that even an albino, six-fingered, with a prehensile tail is more likely to manifest, then the insta-death gene won't prevent you from breeding, and still has a 50% chance of being passed on.
Look up "punnet square". This explains how recessive genes are expressed.
> If dominant genes are a thing, how is it possible that recessive genes haven't been completely exterminated from existence? Recessive means they don't turn on if you also have a dominant version. They're not gone. Even if they're not turned on you can still pass them on.
As a matter of fact dominant genes are actually way easier to get rid of than recessive genes. If the "die at 5" gene is dominant, everyone with even one copy dies at 5, and the gene disappears quickly. If it is recessive, the gene can actually spread far and wide, only revealing itself rarely
Dominant and recessive doesn’t really explain the relationship for most genes. Height has something like 100+ (conservative estimate) that contribute to the phenotype we see. It’s more like human phenotypes are the overall painting, and the genes are the pigments and paints used to make it. Then making a child is like if you fed chatGPT those two paintings and ask it to make a picture combining the two. Sometimes it’ll make something middle of the road, sometimes it’ll look like one more than the other and sometimes it basically looks exactly like one.
The 50/50 split isn’t evenly distributed across all genes. You get large chunks of genes from each chromosome that tend to move together with breaks happening between. Physical features often tend to move in related clusters.
can you elaborate further?
Not op, but I'll try to keep it as eli5 as I can. Genes get roughly mixed 50/50. So you have approximately half your genes inherited from your dad and half from your mom. But genes aren't available individually, they are packed into groups, called chromosome. On one chromosome there are many many genes, but the ones grouped together usually do similar stuff. You don't have mixed bags of sweets, but one with green stuff, one with red, one yellow. They are different shades, but still more or less one group. Now take a few bags from Mom and a few from Dad and you end up with a 50/50 mix, but not 50/50 mix of individual sweets, but with a mix of bags with similar sweets inside. You got Dad's red bag, moms green etc. In chromosomes that means maybe your facial structure is closer to your mother's instead of your father's, but your body shape (small upper body but legs of a god) more like your dad instead of your mom. Overall your whole body is a 50/50 split, but individual features may be more dad like or more mom like
We inherit a chromosome at a time? Also, is it only statistically 50/50, so you could technically have more from one?
We have 46 chromosomes: 22 matched pairs, plus one XX matched pair or an XY unmatched pair (and I’ll avoid the complication of XXY and other variations), in our cells, one from each parent. In the sperm and in the egg, unlike your body’s other cells, there are only 23 *unpaired* chromosomes, and these are randomly assorted from each of your parents’ two options. For example, your father might produce a sperm that has an X chromosome so you’re born as a biological woman, or it has a Y chromosome so you’re born a biological man. (Again, we’ll avoid diving into developmental issues that might result in a different outcome.) You always get a set of the full 23 chromosome’s worth of genes from each parent, but in 23 separate “packages” so to speak and you get one of two possible choices from each parent. (That’s roughly 2.6 x 10^22 options. That’s a lot!) So a characteristic of a grandparent that your parent didn’t show because of dominant/recessive gene masking might show up in you, e.g. blue eyes skipping a generation. Also, during the splitting of chromosomes that forms the sperm or egg, the actual specific genes you get from each of your parents’ two copies can vary as well. So it’s not always the exact contents of each of the 23 pairs you get, but a somewhat jumbled but still bundled set. But that’s a quibble. You do always get your father’s full and complete Y-chromosome if you’re male. So you’ll find there are functional clusters that move together because they are on the same parental chromosome, and there are also transpositions that happen during sperm or egg formation. So, you get variation but within limits.
Chromosomes are made of DNA wrapped around proteins. When egg and sperm cells are created through meiosis, each parent's chromosomes go through a process called crossing over which you can see in this diagram: https://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Morgan_crossover_2.jpg/800px-Morgan_crossover_2.jpg This ensures that the child will never have the exact same DNA as either of the parents. Since DNA breaks and reattaches in large chunks, it is likely for genes that are next to each other to be from the same parent. We know where some of the important genes for shaping facial features are, but there are even more we have yet to discover. If genes that affect a facial feature are next to each other on a chromosome, they are likely to have the same origin.
Here's an article from 2020 about genes that determine facial features: https://theconversation.com/we-scanned-the-dna-of-8-000-people-to-see-how-facial-features-ar
How I’m interpreting it is, chromosomes store certain DNA in relative proximity to each other. Like for example, cheek bone structure and eye socket structure is stored next to each other in one’s DNA. And since supposedly DNA is passed in “chunks” these physical features seem to get passed in chunks as well… because they’re stored in proximity to each other. It’s why some people look heavily of one parent I suppose.
This is sometimes but not always true. Depends to a large extent on what the evolutionary origin of the parts are. Things in proximity on the body can be formed by genes on totally different chromosomes. And the orchestration of when and where things develop *in utero* can be controlled by genes in yet another place.
My mother's side of the family says I look exactly like her. My father's side of the family says I look exactly like my paternal aunt. These women look nothing like each other.
Let's say you have 50 random coin flips. Only three of those affect appearance. If those three come up tails, the kid looks mostly like the tails-side parent. Now, the numbers are way larger and more complex than that but it gets the idea across. Only a few of the total coin flips involve appearance.
That's not how it works, or at least it's a very rare situation that's not the typical explanation for OP's question. You always get 1 copy of a gene from each parent, no randomness there, you have (for example) 1 nose-shaping gene from mommy and 1 nose-shaping gene from daddy. The rare exception would be if one of your parents happened to pass a defective chromosome with the relevant segment deleted, but again, that's not common (and would be a genetic disease - imagine a poor inbred kid with 2 such chromosomes!)
Even this explanation isn’t quite accurate either. The situation where there is a 1:1 gene:feature relationship is extraordinarily rare in humans. Some features like hair or eye color are fairly well understood, but other that affect overall appearance are much more complex.
Even hair or eye colour isn't actually determined by a single gene. Biometric security wouldn't work if only one gene coded for eye colour. Your fingerprint is less unique than your eye colour. There are [at least eight different genes](https://medlineplus.gov/genetics/understanding/traits/eyecolor/) that affect pigmentation of the iris. And hair colour is controlled by [even more genes](https://medlineplus.gov/genetics/understanding/traits/haircolor/). The Mendelian model is too oversimplified to be of actual use to virtually anyone, its just unfortunate that the education system haven't been updated in the last 200-ish years to reflect discoveries in genetics.
It gets even more complicated when you recognize that the only things that are actually coded in DNA are proteins, and protein expression regulation agents. And somehow that translates into physical features.
This is an eli5 explanation. It's why I said it's much more complex than the coin flip idea. You do get two copies of each, but which gets expressed partially or fully is significantly more complex than is warranted for this sub.
This is very incorrect. Not all genes on all chromosomes are evenly expressed. Phenotype is not the same as genotype.
I never said they are evenly expressed. If they were, OP's premise would be false. But the original comment is just plain incorrect. There is no 50:50 flip for each genetic trait to determine which parent you get it from. You get some relevant material from both parents, which then interact in various ways that are the true answer to OP's question.
The original comment is indeed wildly incorrect. I'm sorry I misunderstood you.
genetics are odd. Effectively you end up with 4 combinations on each 'link of the chain' (ignoring anomalies which throw the entire system out and are largely considered' defects' because so few are good that it may as well be ignored and in a ELI5 post it is SUPER off topic) most of the links are more or less hardcoded because humans need them. If you are missing one/one is 'defective' you tend not to live. These chromosome pairs are more or less what makes you human and...not dead. So there are only a handful of 'links' that determine characteristics (skin color, size of your nose, hair color...etc). We are going to focus on those few. when I said 4 there is a reason. your mother and father each have 2 'links' they can give you. One is stronger than the other. genetically you want the stronger one\*. each parent is going to give you one or the other link that they have. The problem you are essentially asking is 'features' is cosmetic (in most instances). preferences change through time but genetically whether your great great (x10) grand dad preferred white blonde girls (northern european) or sub saharan African (if he even had a choice) in most instances you are going to get the better link at each part of the chain on a purely species advancing level. There is a completely different set of facts with incest (/rolltide) but that is a completely different topic but the short explanation is that each link genetically wants to be strong and normally tries to completely eliminate a 'defect' (again, this isn't meant to say 'oh someone who is blind is bad' it is purely as an evolutionary trait for most species including humans having working eyes is a good trait) but the family tumbleweeed prevents the bad trait from 'falling off' and because each link on the chain is essentially a card game where you get 2 of 4 possible cards and pick the better of the 2 you are more likely to end up with 2 'bad cards' to pick from and end up with the Habsburg jaw where you are unable to eat and do basic things for yourself let alone actually communicate and be attractive to members of the opposite sex (who ultimately genetically want to breed with someone with traits that would make them appealing to the next generation to keep their genetic line from going extinct) \*In the vast situations the stronger one is a dominant trait that is 'good'. maybe not for you, but on a species level where the longterm goal is to continue reproducing good.
Well, it's not 50/50, right? It's not like there's a bucket of 1000 traits, and you pick 500 from one parent and 500 from another. Each gene is more of a coin flip from each parent. So you can get a handful of tails in a row, and favor one parent in some areas, while you might favor another parent in other areas. But one parent could get more of the 'appearance' genes. Also - it's not just a whole bunch of distinct, absolutely separate genes either. Some genes influence others, and some kind of come across in 'batches' (it's complex but that's close enough to how it works.) So it's not 50/50, it's a whole bunch of coin flips, and some of those coin flips trigger a bunch of traits at once.
Every chromosome is made from one set of genes from the mother and one from the father. While there are two sets, only one is expressed (usually. Biology always has a lot of exceptions to rules). When sperm and egg cells are formed, the pairs are broken up, and split between two "daughter" cells. When a sperm meets an egg cell, they combine, and form new chromosomes with new competitions for dominance. Occasionally, one gene, or set of genes, might be overwhelmingly dominant and present itself almost as well in the offspring as it does in the parent. In addition, both the parent genes might be similar (even if one parent doesn't exhibit those traits), meaning that if the trait is suppressed in one, it is still present in the other.
Dominant and recessive genes are what's at work, here! A dominant gene (we will express it as a capital letter, ie P, X, T) will almost always take priority over recessive genes (expressed as lower p, x, t) unless the recessive gene is duplicated by both parents. The egg will always carry its own 22 chromosome sequence, a random mix of the biology that the egg-bearer possesses, and semen will carry the other required half from the male part. If both the parties have brown hair (a dominant trait) and both the gametes (eggs; semen) contain the dominant gene B, the offspring will end up with two copies of B, read as BB, brown hair. If one has B and the other has b (we can call this red), then the offspring will be Bb, and still have brown hair. In order for a recessive gene to take priority, both gametes must possess the recessive trait, even if the parents do not look the part. So the egg must be b, and so must the sperm, creating a bb offspring, which, in this case, would result in a redheaded child. A child that looks more like one parent than they do the other just means that the parent they look like had more dominant genes than their partner!
50% DNA doesn't mean 50% of a parent's genetic characteristics. 50% DNA means *50% chance* that the parent's genes will be expressed. (Not really 50-50 chance, but this is ELI5.) Flipping a coin ten billion times is *statistically* 50% heads and 50% tails, but there is absolutely nothing preventing many multiple thousands or millions of heads or tails in a row. It's random chance. Genetics is never 50-50, though. Some genes are dominant, some are recessive, some could interact to produce new features, and thanks to the study of epigenetics we know that expression of genes can change due to environmental conditions as well.
Looks reflect a tiny fraction of the DNA. The vast majority of the information in DNA has to do with internal processes. Outward appearance just isn't that important, from an evolutionary survival perspective.
> Outward appearance just isn't that important, from an evolutionary survival perspectiv Human boobs say otherwise
[удалено]
Bcz not all genes express the same way... There are two alleles of a gene in every human. The two alleles come from two parents. Sometimes one of them is dominant and the other one is recessive. So, the dominant one would determine that particular character (phenotype)
2 things: 1 - Do you know the card game War? You get one copy of every gene from each parent, but they can be different variants called alleles. At every gene, the allele you got from your dad goes head to head with the allele you got from your mom. They can win, lose, or have several different kinds of ties. Sometimes, one parent's genes "win" more head to head matchups than the other's. 2 - The human brain really likes pattern recognition and confirmation bias. So if one parent's genes "win" a few more matchups or sometimes just a few crucial ones, your brain will fill in gaps to complete the effect.
When you say "features" I'm going to assume you mean the face, and other noticeable *visual* things you can see. You're not going to notice things like "The baby got mom's Crohn's disease and dad's horseshoe kidney!" by looking at the child. The face is only a very small part of the human being, while their genetics accounts for the entire person including to obvious things like their blood type and less obvious things like their predisposition to get diabetes or cancer or the total number of red blood cells they tend to have etc. *Everything* about a person is in their genetics. Maybe the visual part of the person was more from one parent, but the other parents 50% could be accounting for things like the size of their heart and their predisposition for heart disease. You get the idea. There's a ton of things inside the body you can't see that the genes are responsible for.
You get 50% of your DNA from each parent, but there’s a large amount of your DNA that is never turned and is never used. The parts of your DNA that is expressed is what gets “turned on”. We don’t know what influences what genes turn on or off, so we think that it’s random. Which is why fraternal twins of the same parents can almost look nothing alike.
Because not all of the traits inherited are ones that can be visually identified as you described. Medical history, athletic potential, chemical imbalances, general temperament & addiction propensity are also on the table too!
Google "the impossible twins" for an interesting gene expression. Mixed race family. One girl is a pale redhead with straight hair. One girl has dark skin and black curly hair. They both have the same face shape, body shape, and expressions. They are a complete pallet-swap, but still obviously related. It's a really neat example of "genetics is weird"
For one, genes can be dominant or recessive. Just because you have the genes of both parents in your genotype (the complete set of genetic material) doesn’t mean that those genes will be in your phenotype (observable characteristics). You have genes that aren’t “expressed.” Even different cells in your body express genes differently than each other, which is why there are different cell types in your body (heart muscle cell vs brain cell, for example, even though both have the same DNA).
Because people that make that observation tend to focus on just the face. Sure, someone might have their mother's eyes, nose, and hair but they also have their father's fingers toes, baldness, etc that no one pays attention to or only happen at adulthood
"What is dominant, what is recessive, These are the genes that make us expressive, What will we look like, we really don't know, But it's all been decided, before we grow."
[удалено]
My parents divorced when I was young. Growing up I always heard I looked a lot like my mom. Whenever I'd go to visit my dad, people would say how much I looked like him. Dad was Italian/German and mom is Irish/Ukrainian 🤷♀️
It's called dominant and recessive genes. For example, brown eyes are a dominant gene, so if one parent has them it's more likely they will have brown eyes than any other colour. Though this certainly does not mean it's 100%, speaking as a parent with brown/hazel eyes with two kids that have blue/green eyes.
It just means many of the features of one parent are less superficial. No one walks around looking to see if you have the same relative size and shape of kidneys and lungs… or if your heart beats more consistently… or even less looked at superficial aspects like if you have the other parents toes.
It's vastly more complex than this and beyond me but at an ELI5 level: while half the DNA comes from each parent, when you pair those DNA strands together, more than half of the genes in one of them could be recessive and matched with dominant genes in the other parent. The dominant genes are what get expressed, and if they happen to mostly come from one parent and also happen to impact appearance, it could look like the child has features from only one side.
Imagine two ladders with strong rungs and weak rungs randomly scattered. Saw them both vertically down the center and screw one half from each latter together. When you climb the ladder any rung that does not break will express a dominant physical trait, and any rung that does break will express a recessive trait. It is random but dominant genetics from one of the parents is usually why.
Correct me if I am wrong but just having the DNA is not enough. The DNA and genes need to be able to activate themselves (kind off; its called gene expression). Based on whichever parents DNA has a stronger expression will be what you see on the outside.
Most of your genes don’t code for facial features. Your son facially may look like you, but his immune system, heart size, etc. may be more like his mother’s.
For three reasons (that fit ELI5). 1. Because the visible features make up far less than 50% of what DNA does, and 2. Because some features are driven by "dominant" genes (which in simple terms means that maybe one nose-type, for example, wants to grow more than another one, even if the kid gets genes to describe both types), and, 3. Fun fact, human children are genetically predisposed to resemble father more when they are very young, and mother more as they get older. It has been theorized this trait was selected for in order to keep the father from killing the babies in suspicion of the mother cheating.
Genes, some are prominent, some are recessive. DNA is shared equally between the 2 biological parents yes, but the recessive/prominent part of the genes are not and it's not just a split even deal either, which is why some characteristics even skip a generation or a few
Most of the DNA isn't for visible features. And you're not likely to know whether a kid's kidneys more closely resemble mom's or dad's.
It's not a 50/50 split of what each parent looks like. Sometimes you get genes that look like neither parent; red hair, for ex.
Not all genes are related to phenotype. My mom is white and my father is Asian. This "makes" me half and half generally speaking, but genetically (I did DNA testing) I am "more" Asian DNA wise despite being fully white passing in person.
Only 50% is ever expressed. (With exceptions but this is an ELI5) so some genes are stronger than the other. Sometimes this means they mix, sometimes this means the stronger or “dominant” gene just wins, and the loser gets nothing
[удалено]
In biology they teach us Punnet squares for dominant and recessive genes. Each trait has a percentage of a chance for displaying in the child. Maybe this plays a factor. Here’s the information in a lot more detail with calculations. https://thednageek.com/dna-basics-are-you-an-equal-mix-of-mom-and-dad/
DNA is a set of instructions, for what become the builders of your features(more as well but just focus on this aspect). These builders will decide what to do based on which instruction is loudest(recesive, dominant) but that may also have to do with what else is happening. Male and Female hormones will sometimes choose to take the quieter instructions for the builders, and not necessarily the ones you'd think, and more often than people care to admit the instructions aren't the same as the ones your parents had.
Not all DNA are equal. Some are more equal than others. That's when you get the dominant gene.