I have a genetics question that might make me look super stupid

[Deminism]

If a child looks like someone in their family are they also likely to have their character traits and illnesses or are they inherited differently?

DD looks the spitting image of MIL. Does that mean she will be similar to her in other ways?

This seems like a v basic question but google not helping?

You inherit different traits through different genes. Inheriting one set of genes does not necessarily mean you'll inherit another set of genes. So she might be similiar in personality to your MIL or she might not.

I would say she's more likely to turn out similar if told she will, though - self fulfilling prophecy and all that.

Not in any way linked

I totally get your question. DH has a generic heart condition. When he was diagnosed our 3 children had to be tested. Two of them (DS1 and DD) look exactly like me. DS2 looks exactly like DH. He is the only one not to have it, we were all stupidly surprised. DS3 is also his mini me had yet to be tested but he is also very physically similar to DH.

...... and I would also say that 'nurture' (upbringing) has a LOT of influence on your personality.

My ds and dh have exactly the same mannerisms.
They are not genetically related.

It is impossible to say for every character trait and illness but for the majority no, for several reasons. 1. Genes are contained on chromosomes. There are 23 pairs of chromosomes. Traits contained on different chromosomes will be inherited independently. 2. For each pair of chromosomes, 1 is inherited from each parent, so 50 percent of our genes are going to come from the other side of the family. 3. Some of these genes may be dominant or recessive. For a recessive one to show up it has to be inherited from both parents, not just one. 4. In many cases, especially with personality, environment also has an influence, so how someone is brought up will also influence how they turn out.

More importantly, why are you worrying about this? Please see your daughter as the individual she is.

For what it is worth, my daughter is the spitting image of her father's side of the family, but reminds me often of my little sister in how she acts. But she is also very much her own little person too.

Girls inherit their X chromosome from their father, who inherits it from his mother. The X chromosome doesn't actually change much over time so it will be exactly the same in a DD as her paternal grandmother. So perhaps there are traits there that have come through in your DD.

(Reading into genetic genealogy and becoming a self taught nerd)

My DD has DH's eyes, just like MIL's, other than that she looks just like me!

My sister looks exactly like my mum's sister , the red hair, the figure everything. But do not both have the same illnesses or personalities. I have inherited a gene from my dad that causes cancer but my sister has not I look.more like my dad' than she does but not exactly. Genetics is like a roll of the dice but the genes are not usually all inherited together

No don't worry! She can inherit your MIL's face but whatever genes are connected to personality (and nature/nurture debates continue) they're not connected to the genes for facial features.

Without going into the science as there are far more qualified people than me who could answer that but I look very similar to both my mother and grandmother and am nothing like either of them! I have some traits like a love of reading or similar taste in some things or sometimes a similar mannerism but I'm a very very different person to either of them

Tuh. As I've gotten older I've become my DM! Even down to the sound of my voice, my hands have morphed into hers, our laughs are the same and we finish each others jokes (its actually adorable really.) We do also have the same ailments (exact same gammy knee, bad hearts and blood pressure issues - although mines are more minor) So! Take from that what you will lol.

Well that's a big question. Short answer no, character traits and looks are not genetically dependent on each other. Longer answer... some traits are are more dominant and some are more heritable. So for example how satisfied you are with your job is heritable, but not very strongly. So you aren't guaranteed to be like that if your mother was. Just slightly more likely than the average.

Some character traits are fairly strongly heritable. Bizarrely, openness is more heritable than extroversion. So two open parents are more likely to get an open child.

And (this is less based on science!) I've been told some traits are close on the genome and therefore more likely to be inherited together. So an example floated to me was predisposition to schizophrenia and artistic expression. That one is really tenuous.

So I suppose if a strongly heritable physical trait was close to a strongly heritable character trait, it could be more likely.

You are forgetting that your daughter is 50% you.

Even though she has acquired some genes from her father that make her look like her MIL, that does not mean that she will have the same personality. As far as I'm aware there is not a solid genetic basis for personality, and even if there turns out to be, we know that genes can be influenced by the environment. This is where the whole 'nature vs nurture' debate comes in.

If your MIL has a genetic disorder, it could be passed on to your husband and then your daughter, but as a previous poster has said there are dominant genetic diseases, where you only need one copy of the faulty gene (I.E from one parent), and recessive, such as cystic fibrosis, where your daughter would need the faulty gene from both yourself and her dad.

A lot of diseases have somewhat of a genetic basis (Alzheimers, Parkinsons etc), and we have identified genes that can increase or decrease the odds of you getting such disease. However unlike the dominant and recessive diseases mentioned above, it is not the case of a single gene, and it is often a combination of a number of genes and the environment coming together. So for example your daughter could have a gene from your husband (inherited from MIL) that raises the risk of heart disease, but then she could have 5 gene alleles from you that have a protective effect and decrease the odds of heart disease, so overall her odds are good.

To answer why I want to know. Similar reason to @Dontstepinthecowpat re a genetic condition mil had likely to be carried by 50% of our children. I am interested to know if the child who looks most like mil is also most likely to have it? Also we have two DSs. One looks like dh and one looks like me. The one who looks like dh also has similar personality to dh. I am interested to know if this is more likely due to the same genetics that make him look similar.

Basically, no.

Imagine that you and your DH each have a deck of card. Each card is a different genetically-influenced trait, e.g. height, eye colour, sense of humour, hair texture, temper, facial structure and so on.

When you have a daughter, half of your cards are duplicated at random to form her deck of cards, and half of your husband's, again at random. Your daughter's deck is now 50% the same as yours and 50% the same as her father's.

So a daughter could potentially look very clearly like you, because she had inherited that from you, and have a personality that was all your husband's.

This happens every generation, so ultimately each of your children daughter should, on average, share roughly 25% of their genetic heritage with your MIL, and it's a random quarter.

^That's the basic answer.

However, the more complex answer is that each card in your deck (and your husband's deck) has got a multiple traits written on it. So sometimes inheriting one trait (e.g. toe length) might be tied to sense of smell. So although the cards are still random, they are random groups of traits. If you magically knew your genetic code and your husband's and all your relatives' codes, you might be able to guess that your daughter was going to be short-sighted because she had something random like an asymmetrical parting in her hair. But you don't, so you can't.

And the even more complex answer is that even if you did have such knowledge, it might not help, because sometimes, in the great assembly line that is reproduction, cards actually get cut in half and swap tops and bottoms with other cards, to make new cards. So that bunch of traits that you thought usually went together, now... don't!

@Schlobbob women have two X chromosomes, one from their mother one from their father. Men have one X chromosome which always comes from their mother (and a Y chromosome from their father). So yes you're right that one of the DD's X chromosomes will come largely from the MIL, but they also have another from their maternal side of the family.

Everyone (except in some diseases) also has 22 pairs of non-sex-linked chromosomes, (named imaginatively 1-22) one of which comes from their mother one from their father. However as @JamieVardysHavingAParty describes each complete chromosome isn't passed as a whole from one generation to the next but they are matched in their pairs and bits are swapped between them.

There are then additional complications as to whether genes are expressed or not (some genes you only want one copy to be active, so one effectively gets switched off), dominant (you only need one copy to get a trait) or recessive (you need two copies to get the trait).

So as others have said, for most traits, a child which looks like a relative will have no higher a chance of carrying other traits of that relative than any of their siblings.

Is there a specific illness you're concerned about? If so, do you know if the father of your DD is a carrier?

[ @Schlobbob it's not true that the X chromosome passes mostly unchanged through the generations, in each female generation the two X's pair up like all the other chromosomes and swap pieces. It is the Y chromosome which passes largely unchanged down the male line, as it never has matching Y to pair up with and swap bits with (though there are a few genes which are present on both X and Y, and sections can be swapped between these)]

@AndAnotherNameChanger there is but it is outing as relatively rare. It is a type of muscular dystrophy. Dh is a carrier. I think I have read that all our kids will be carriers but only 50% chance of having it. And severity is different for every person who has it as is rare of progression.

Rate not rare

That is a very good analogy @JamieVardysHavingAParty

This sounds like your family should be receiving specific advice from a genetic counsellor. You shouldn't have to be seeking explanations about this on the internet.

If you haven't already, please ask your GP if s/he can make a referral.

We have been told there is no advantage in knowing whether they have it or not as all it will do is affect our expectation of why they can achieve and therefore affect us encouraging them to be active.

I can see that argument, but it's left you with a lot of questions. I do think part of post-diagnosis support for your family should have included a specialist explaining this, rather than forcing you to turn to randomers to give you the Cliff Notes on genetic heritance. (Incidentally, if you want to know about this in more detail, the key search term is meiosis.)

You are forgetting that your daughter is 50% you.

I get impression the genetics aren't that simple... We get copies of each gene from each parent. When they combine at moment of conception (my crude grasp of the science), somehow only one copy of each gene will be expressed. In theory, only all of dad's genes or only all of mom's genes will be expressed. So the child could seem like a clone of the parent. The child still carries the other parent's genes and can pass them to own children, but one parent's genes may not be expressed or apparent at all in the offspring.

Say I'm wrong.

Sorry what I said isn't much help to OP! Genes are funny things.

I might have this wrong but...

If your DH is a carrier that suggests to me that it's a recessive gene, ie you need one from both parents in order to actually have the condition.

If this is the case then you'd need to be a carrier too for there to be a risk of them being affected.