from ThinkProgress.org. The concept will not appeal to people whose view of genetics is that "one gene" explains everything - there is not "one gene" that determines most traits - they are combinations of genes and biological processing of the genetic information. It goes like this:
The gene or genes is/are on the X chromosome, so carried by the mother.
When women carry the gene, they are more likely to have more children. These women apparently have a trait that makes them more attractive to men. (or more attracted TO men?). According to the article, "Not only are they more fertile and have less complications during pregnancy, but these women are also more extroverted and have few family problems and social anxieties."
When men carry the gene, they are more attracted TO men.
Since this gene(s) is on the X chromosome, its presence increases reproduction of females, so is passed on to future generations. Like male pattern baldness, it's passed mainly via the maternal lineage.
The authors note, "This is called the “balancing selection hypothesis,” and it effectively demonstrates how male homosexuality —as documented not only in humans but hundreds of species — does not actually contradict expectations that evolution favors reproduction.
I guess, try explaining that to the small minded "If everyone was homosexual, there would be no people left" people. The same inherited trait that makes men want men, could make women more fecund, perpetuating male same-sex orientation.
The authors are also careful to note, sexuality is determined by multiple factors, and is not as simplistic as one gene or one intrauterine effect. Also, while this issue relates to male sexual orientation, there are implications for female sexual orientation.
I was skeptical at first when reading that story, but the more I thought about it, the more it made sense. There is no gene for anything. Genes manifest differently depending on different environmental conditions, but the notion that there's a gene for being gay, just as there's a gene for being smarter, shows a fundamental lack of understanding on the part of most people of what a gene is and what it does. A gene for homosexuality has no advantage, but a gene designed to make females more attractive to males that also makes its way into the bodies of males has some potential.
So from an evolutionary biology standpoint, this theory holds some water, because it manages to explain how this gene has fecundity and how it manifests in both males and females. I'm looking forward to hearing more about this in the coming years, and curious what Dawkins (the evolutionary biologist) has to say about this story.
"Mothers and maternal aunts of gay men tend to have significantly more offspring than those of straight men."
This reminds me of a study I recall hearing about in the past which seemed to indicate that the more offspring a mother had, there was a higher chance the later-born children would be homosexual. This had something to do with a natural decline (possibly of hormones? I can't recall) that occurs in woman. Apparently this (hormonal?) decline, during the years of having multiple births, can affect the outcome for sexual orientation.
Anyone familiar with this?
Bottom line: yes, sexual orientation is very complex and is contingent on many continuously changing factors and cannot be attributed to one "gay gene." This is why we have gay, straight, bi, intersex, both sex, etc. It's all natural, Baby! Embrace it!
for some reason the text editor is acting up, so I'll try again.
I think you are right about the complexity issue. Here is a meta-analysis on birth order and handedness: here. In meta-analysis, data is combined from multiple prior studies, to increase the sample size and summarize the results. There are hazards, but statistical methods are designed to work out the issues.
In this case, handedness and sexual orientation were examined. It turns out that, if you are gay, you are 34% more likely to be left handed (or non-right-handed) than if you are hetero male. As for birth order, if you are right handed and you have prior male siblings from the same mother, then you are more likely to turn out gay.
I find this strange and I don't know if their purported causes are valid - specifically, that anti-male antibodies are produced during pregnancy with a male fetus, which affects subsequent male fetus.
What has not been found is that "gay" is a "choice", or caused by parenting issues, or is due to "recruitment".
Sentient, I am so glad to read this report. I have "known" for a long time that homosexuality was natural but had no concrete evidence I could us when debating that point. All I had was my intuition. However, I have known so many homosexuals in my life I was easily able to put aside homophobia in favor of natural processes.
There was a time when I wished I were homosexual, but it just ain't so. I am stuck with heterosexuality and in the process learned to be anti-sexual.
When I taught in prison, my students brought in a lot of fellow prisoners to my classes because they knew I was compassionate about their life experiences and we discussed ways to feel comfortable and confident in their own being. I became known as the teacher of homosexual prisoners, not by design, but by effect.
In some ways it's easier. You both largely speak the same language, sexually, emotionally and psychologically. Unfortunately you get the worst parts of each sex colliding into each other (such as stubborn male pride), but that's the reality of any human relationship. Frankly, I feel sorry for straight guys and the straight women who put up with them!