personal genomics; eye color; sexual selection: cognitive vs genetic

[gusl]

If I get my DNA sequenced at 23andMe or DecodeMe, what information do I get? Is my privacy safe?

If my parents do it too, will it tell me where recombination happened in each chromosome? Btw, does anyone know of a visualization of the chromosomes showing some genes (and corresponding phenotypes)?

Kinda like this but more general-purpose and for laypeople.

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Apparently, there is uncertainty about exactly which chromosomes contain genes related to eye color. GNXP.

As much as I dislike popsci, being a layman, this looks like the best explanation that I can understand (of the ones I could find through Google) of the fact that two blue-eyed parents can have a brown-eyed child:

Eye color is a complex trait that depends on the state of several interacting genes. The gene that usually decides the issue (blue eyes or brown eyes) is the OCA2 gene on chromosome 15. But it comes in different strengths. A person with a weak form of the OCA2 gene will have blue eyes. Likewise a person with a strong form will have brown eyes.

The plot thickens, though, because an individual also has other eye-color genes that each has a say in the final eye-color outcome. For example, if one of these lesser genes is strong, it can make the weak form (blue) of OCA2 work much more effectively — almost like the strong form (brown). Then the eye color may be a light brown or muddy grey. In fact, the resulting color can be any shade of brown, hazel/green, or blue depending on the strengths of the interactions.

Of course, there's mutation, but I'd expect that to be too rare to explain this phenomenon.

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Now, blue-blue couples almost always have blue-eyed kids. This article is about the theory that blue-eyed men are more attracted to blue-eyed women because cheating would be easy to catch... of course, this wouldn't be that useful in populations where >%80 of the men are blue-eyed (and most of the others are heterozygotes).

So should we expect this effect to be stronger in more mixed populations? I imagine so; not because the blue-eyed men in those regions have stronger genes for blue-eye preference (this is bordering on silly), but because sexual attraction has a cognitive component. (The cognitive theory predicts adaptation within 1 generation; the natural selection theory would require many. But my main reason for believing the former is that the idea of such a specific gene sounds silly.)

In any case, this suggests that blue-eyed kids have enjoyed more paternal attention than brown-eyed kids.

The natural selection theory (though I'm not sure if anyone believes it) would be an instance of a common fallacy: "there's a gene for everything, no matter how specific".

Comments

[http://users.livejournal.com/_tove/]

This article is about the theory that blue-eyed men are more attracted to blue-eyed women because cheating would be easy to catch... of course, this wouldn't be that useful in populations where >%80 of the men are blue-eyed.

Also, a lot of babies have blue eyes, even if they grow up to have another color, so this would be an incredibly slow test (in addition to being entirely inconclusive).

As far as I understand it, eye color is not only caused by several genes with several "strengths," it is also the product of more than one physical structure in the eye.

[surrey-sucks.livejournal.com]

I did terribly in my genetics class, gene interaction being the most challenging part for me.

Funnily enough, I never notice people's eye color, even when they have been my partner for years. Maybe it's because I'm short and looking in their eyes is difficult!

[isomorphisms.livejournal.com]

Thanks for posting that explanation; I'd always wondered where the other eye colours came from, as the usual bare-bones popsci explanations make it sound like everyone will have either brown or blue eyes, and the same shade, at that.

[afanesvoltaje.livejournal.com]

I've totally been pondering this very subject!! I had been playing with a theory last year about whether men vs women should preferentially be attracted to someone who stands out genetically in their population.... and then lately, puzzled by the fact that my baby still seems to have very blue eyes at 4 months (I know it's not settled 'til 6, but I still expected to see them start to change by now!) despite my husband being Indian, I'd been wondering quite how it actually worked, including how you end up with hazel.

Thanks for posting a synopsis of just the info I'd been wanting but not yet taken the time to dig up myself!

(of course, now that I know someone got a publication out of a simple idea I'd been playing with I'm kind of jealous...)

[gustavolacerda.livejournal.com]

Your baby must be 6 months old by now. What color are they now?

[afanesvoltaje.livejournal.com]

You're right on time - I'm impressed.

And... they're still blue! They're sort of a blue/grey... but definitely not brown.

[gustavolacerda.livejournal.com]

I've met a surprising number of half-Indian people with blue eyes. At CMU, I remember one of them who was 100% Indian.

[afanesvoltaje.livejournal.com]

I hear about it for some north Indians... but it's awfully strange for a south indian. Although there are people with hazel eyes in my husband's family.