novice genetics question

[rawalmond]

alright so i'm a novice when it comes to science, don't know much about it... at all. probably couldn't even pass grade school quizzes if they were presented to me. so i have no idea how genetics work, but i have a question i'd like to be answered, please.

 

a friend of mine's mother is white, and his father is half black and half latino. another friend of mine is trying to argue that he's 1/3rd black, 1/3rd white, and 1/3rd latino. but that doesn't really seem to add up in my head.

 

i figure he's half white, a quarter black, and a quarter latino. please correct me if i'm wrong, or let me know if i'm right.

[Moontanman]

alright so i'm a novice when it comes to science, don't know much about it... at all. probably couldn't even pass grade school quizzes if they were presented to me. so i have no idea how genetics work, but i have a question i'd like to be answered, please.

 

a friend of mine's mother is white, and his father is half black and half latino. another friend of mine is trying to argue that he's 1/3rd black, 1/3rd white, and 1/3rd latino. but that doesn't really seem to add up in my head.

 

i figure he's half white, a quarter black, and a quarter latino. please correct me if i'm wrong, or let me know if i'm right.

 

 

My ancestry is Native American, Melungeon, Scottish and African, my eyes are blue my hair is curly and white (used to be dark brown) what color am i? You are making up terms that have no real meaning...

[rawalmond]

i'm not actually looking for a debate on terminology...

[zapatos]

alright so i'm a novice when it comes to science, don't know much about it... at all. probably couldn't even pass grade school quizzes if they were presented to me. so i have no idea how genetics work, but i have a question i'd like to be answered, please.

 

a friend of mine's mother is white, and his father is half black and half latino. another friend of mine is trying to argue that he's 1/3rd black, 1/3rd white, and 1/3rd latino. but that doesn't really seem to add up in my head.

 

i figure he's half white, a quarter black, and a quarter latino. please correct me if i'm wrong, or let me know if i'm right.

Someone please correct me if I'm wrong, but...

 

Your friend has 1/2 of his genes from his mother and 1/2 from his father.

His mother can only give up 'white' genes which makes him half 'white'.

His father can give up 'black' or 'latino' genes, but he doesn't have to give up half of each. Your friend could have inherited from his father all 'black' genes, all 'latino' genes, or more likely, something in between.

Edited April 2, 2012 by zapatos

[Xittenn]

Let's put it this way, gene expression is like a recipe for cookies sometimes. What comes out when you bake your cookies can vary depending on a number of factors. So although we have shortbread, chocolate chip, and macaroons, the variations within these types of cookies differs greatly. So if you mixed them you honestly might find that there are a variety of newly formed distinct cookie variations. And simply put, even if you did only come out with one type of cookie there would be a definite variation within that specific cookie type and to put definitive ratios on its origins isn't really possible and doesn't really make sense. Gene expression ensures that there will be a range of melanin production because there are a number of genes that express this functionality. The expression process is complex and not completely fleshed out!

[rawalmond]

you guys are great. love the answers i'm getting aside from one of the replies.

 

but i'm looking for a more simplistic, less scientific answer in this situation. for example, someone comes up to my friend, "what race are you?", he obviously can't answer how much percentage he got from his mom and his dad. he could've got 60% of his genetics from his dad, and 40% from his mom. but how would he answer it in a simplistic way?

 

"i'm half white, quarter black, quarter latino"? would that be right?

or would it be "i'm a third black, a third latino, and a third white"?

[Xittenn]

Again it doesn't work at all like that, each race contains variations in their recipes within the race and these variations overlap. You can not say I am so much part this and so much part that. Not only this but what you call Latino is made up of historical mixes as well. At best you can say give a cultural history of each relative. There are a few indicators, some people have or don't have certain genes and these are recognized as having historical lineages but what you are discussing doesn't exist, it only exists as a cultural thing. Maybe you can have your diffuse/spec map taken and you can hand out your reference material for novel purposes!

[zapatos]

That is what you get when you ask the question on a science site; accuracy instead of simplicity.

 

The problem is that 'white', 'black' and 'latino' are not so simply defined or even have a definition that is agreed upon. And how many genes you get from which ancestor varies. It is like asking "which shade of blue is better, navy or royal?". It doesn't lend itself to an easy answer.

 

But if for you and your friends you want to define 'white' as 'the race his mother is', etc., and you want to assume that genes are distributed evenly, then go ahead with 1/2 1/4 1/4 as being the correct answer. This sounds like more of a math question than a genetics question anyway.

 

You'd get a better answer if you just asked "what percentage of genes come from which ancestor?".

[ecoli]

Add some more complication by the fact that 'latino/hispanic' is not a race, in the traditional sense. Hispanics are some mixture of White, Native american and (seemingly to a lesser extent) African race - thanks to colonial patterns of interbreeding with local populations in the Americas as well as transplanted African slaves.

 

http://blogs.discovermagazine.com/gnxp/2011/04/the-coincidental-intersection-of-sociology-and-genetics/

[CharonY]

Technically we are most likely only discussing a handful of different allele variations. As mentioned, there is nothing like a pure race from which you can derive a fraction of. There are not really shades of something as we are talking only about a tiny percentage in difference. The relationship of their ancestors would provided the strongest impact.

Also, "black", for instance denotes a much larger genetic variance than all other common denominators (such as asian, caucasian etc.) taken together.

[Bioc]

Hi, as the others have stated above, there is no simple answer for that question, at least genetically speaking, because genes recombine randomly, and some are dominant over others, so the question is in the end about a cultural issue. Oversimplifying: a black man and a black woman can have a white baby if the two have the necessary recessive genes, so the baby won't have "black" genes. Also, the definition of "race" in the case of humans is a little loose.

 

In conclusion, I think the only sure thing your friend can say is "My ancestors were...".

[ewmon]

Generally speaking, your "½,¼,¼" description is more accurate than your friends description. He may feel, or had been taught/raised to believe that one ancestry is no more/less important than another, especially with blacks and Hispanics being minorities. His numeric response might be an attempt to say, "part white, part black, and part Hispanic", because he is a mix of significant quantities of all three. It's not as though he's only ¹/₁₆ black, for example.

 

An offspring gets 50% of its genetics from each parent, and although the gene expression may differ slightly, what the offspring donates to its own offspring is its 50/50 mix. And sorry, two Afro-American people cannot have a white baby.

 

I agree with Xittenn though, that most people ask and tell with respect to culture. What should we think of you as? Same thing with "nationality". On the other hand, a doctor might ask as a medical question to get a feel for what sort of genetics a person might have. For example Tay Sachs: A couple has a baby with Tay Sachs, and the doctor asks each of them if they have any blood relatives who are Jewish.

Edited April 5, 2012 by ewmon

[Xittenn]

Gregory S. Barsh. "What Controls Variation in Human Skin Color?"

 

there exists within a section on the Genetics of Skin Color.

 

I'm also asking the question, what about cross over?

[zapatos]

And sorry, two Afro-American people cannot have a white baby.

Are you saying this because it is impossible, or are you saying this because it is exceedingly unlikely?

 

If two black people each had one white and one black parent, isn't it possible, however unlikely, that the offspring of those two black people could inherit only the genes of the white grandparents?

Edited April 7, 2012 by zapatos

[hypervalent_iodine]

Are you saying this because it is impossible, or are you saying this because it is exceedingly unlikely?

 

If two black people each had one white and one black parent, isn't it possible, however unlikely, that the offspring of those two black people could inherit only the genes of the white grandparents?

 

Or even further down the line than that. The other way is if two black parents gave birth to an albino child or if one of them had some as yet undefined genetic mutation. IIRC, there is at least case where this has happened, although the reasons were unclear.

[ewmon]

Are you saying this because it is impossible, or are you saying this because it is exceedingly unlikely?

 

If two black people each had one white and one black parent, isn't it possible, however unlikely, that the offspring of those two black people could inherit only the genes of the white grandparents?

Perhaps I misspoke. It may be that there are so many genes involved with race that it's next to impossible, and so it almost never occurs, but yet it does happen. It's not as though there's one gene for skin color, one for hair texture, etc.

 

I understand from my studies that most racial traits do not involve Mendelian genetics (dominant/recessive genes), and instead, seem to be "blends". Consider something outside race, such as stature. One tall parent and one short parent don't have either tall or short children, but usually something in between.