Could the biology of homosexuality be considered similar to the genetics of eye color?

Question

A recent article on the genetics of eye color said "There is no single gene for eye color," while an article on homosexuality said "Human behavior is way too complex for a single gene to determine sexual behavior."

If both parents have brown eyes, all aunts and uncles have brown eyes, and all grandparents have brown eyes there is still a 7 to 8% chance their child will not be brown eyed. If there is just one aunt or uncle with green or blue eyes, the chance of the child not being brown eyed rises to 11 to 12%. The 11 to 12% range remains constant if aunts or uncles from both parents are not brown eyed.

These percentages resemble scientific studies on the percentage homosexuality.

Although it is not known why being brown eyed is dominant, the assumption of heterosexuality being dominant could be explained as needed to propagate the species. Although brown eyes are dominant, there are still blue and green eyed individuals, as there are still gay homosexual and bisexual individuals.

An analogical example:
% Blue eyed to % gay,
% Grey eyed to % bi with a preference to the same sex,
% Green eyed to % bi with equal gender preference,
% Hazel eyed to % bi with a preference to the opposite sex,
% Brown eyed to % of straight.

When comparing eye colors, it is a metaphor and not intended to suggest a link between sexuality and eye color.

Answer 1

I do think homosexuality is strictly linked to the genes. Of course it may be a polygenic trait, and that is why homosexuality is hard to link to a gene in particular. Environmental factors affect the trait but ONLY because environmental factors affect the genes, not the personality of the individual. Many people think that environmental factors affect the individual emotionally... (somebody above mentioned the environmental factors)
When you link eye color with homosexuality, is it metaphorically speaking? Interesting! I like it!

Answer 2

You assume homosexuality to be biological (I agree) but there are those who think its a choice. There are other things besides genes that could affect someones biological make up. For example, temperature place a very important role in the sexuality of some species. In some species of fish sexuality is determined by the availability of a male. If the male dies then one of the females becomes male. There was a study done years ago that said all homosexuals had an enlarged hypothalamus (this study lacked a control because all of the men were HIV+). I believe that the answer is somewhere between genetic makeup and environmental stimulus. Either way I don't think its a choice.

Answer 3

I don't know the answer to this question, and I am really confident that no one does. You point out some good observations. Let me add to those one interesting piece of info. While association studies have been useful in finding genes that corelate with other complex geentic traits, genes that are correlated to homosexuality have proven allusive.

There are two ways to interpret these findings. One possiblility is that different unique combinations of alleles lead to homosexual preference in different people. This makes association studies almost useless. Another is that there is an enviromental component that plays a role in determining sexual preference in many individuals. This component may differ in importance with the environmental influence being negligible in some, and extremely significant in others. This would really foul up any genetic studies. A variety of potential environmental factors have been proposed including things as diverse as uterine environment to sexual abuse in childhood.

In my opinion, when we try to decipher the root causes of something like sexual preference, we miss the point. Whatever the reason some people choose to partner with the same sex, as long as they take joy and comfort from that, it shouldn't matter why. The fact that some need to find a genetic cause to either support the validity of that choice, or to label it a genetic disease, says more about our society than it does about biology.

Answer 4

Actually, the only 2 studies that ever found a 'difference' between straight men and gay, were not DNA based. The study about Birth Order and the number of male children proved that gay males were on average at least the 3rd son born or later, with the % for being gay going up the further down the line of birth. They postulated that the mother formed some form of antibodies while carrying male children, and this reflected in the later children.

The second study was performed on dissecting the brains of gay men who had left their bodies to science. By slicing the brain to certain specific areas, they proved that the measurements were right along the lines of the female brain. It wasn't that the gay men had "female" brains, but the fact that they shared a common size of the parts of the brain affected. Straight men had on average, larger areas than gay men and women in 'general.' While this alone isn't the reason for being gay, it is thought to be a part of the process of how our thoughts form and how they affect the biology of the brain, perhaps nudging us closer to being fabulous! lol

Answer 5

I have no idea if homosexuality is genetic or some other cause. The one thing I know for sure is that a person is born homosexual. I don't equate homosexuality to eye colour but to handedness.

Frankly, I believe sexuality is on a continuum with some people decidedly homosexual, other people decidedly heterosexual and some partway along the range. People smack in the middle of the continuum are the bisexuals among us.

Answer 6

Your question asks if the inheritance "could be" similar. To that, I would have to answer yes. Articles and evidence I have read point more and more to a genetic basis for sexual preference. And, as you noted, there are many variations on that theme. I don't think we can rule anything out as we do not know everything about sexual preference, or most other topics for that matter.