Recently I was listening to one of my favorite dorko-podcasts that I am obsessed with, Keith and the Girl. One of the hosts posited the questions that since identical twins have identical DNA/gene structure- why is it that one can be and the other is not, if being gay is intrinsic.
Being the owner of a gay brother, this bothered me. So I did a little research. I have now concluded that Carter’s genetic makeup, playing “My Little Pony” on a regular basis from 1986-1990, and our ultra-liberal hippie parenting all contributed to his aforementioned gayness. Nature+Nurture+ Mattel products= Guh-guh-gay
“What Twin Studies Tell us about Homosexuality Scientists have studied twins to try and learn if being gay is biologically determined. Studies of identical and fraternal twins suggest that there is a genetic influence on sexual orientation. If being gay were strictly genetic, then in identical twins, there would be a 100% concordance rate for sexual orientation. But one study in 1995 found a 52% correlation for male identical twins and 22% for male fraternal twins. A study on females came up with similar results. If one identical twin was a lesbian, in 48% of cases, the other twin was also a lesbian. For fraternal twins, the concordance was 16%. (source Simon LeVay These studies show that people with the same genetic make up (identical twins) are more likely to share sexual orientation than those with different genetic make up (fraternal twins.) Genetics alone cannot cause sexual orientation, but they do play a part.” The article goes on to say…
“What about the gay brain study? A widely publicized study in 1999 found that a certain part of the hypothalamus was smaller in gay men then in heterosexual men. This study was widely touted at the time as “proof” that one’s sexual orientation is biological and not chosen. But it is not known whether these differences in brain are present at birth or if they occur over a lifetime.” Another article says…
“One reason why conversion might be so difficult is that the brains of gays may be different from their straight counterparts. For example, a couple of studies have been done that show that the brains of gay people are different than those of straight people. And that gay people respond to pheromones differently than straight people.
This isn't surprising, sexual attraction resides in the brain. But where do these changes come from? Are they destined by genes, is it something in the environment or a combination of the two?
The best evidence points to the environment and genes both playing a role.” It goes on to say…
“A number of studies have looked at homosexuality in twins, all with similar results. For example, in one study, if one identical twin was gay, the other was also gay 50% of the time. If they were fraternal twins, they were both gay 22% of the time. And if one was adopted, the chances fell to 11%.
Now these numbers are from one study. Other studies have different percentages but the same trend -- identical twins are more likely to both be gay as compared to fraternal twins.
This strongly suggests that there is a genetic component -- there is something in their genes that makes them more likely to be gay. Genetics, though, isn't everything.
If it were, then identical twins would both be gay 100% of the time. And this clearly isn't the case.
And if it were all environment, then identical twins would both be gay as often as fraternal twins. Again, this isn't the situation.
So the interplay of environment and genes probably results in homosexuality. By environment, I don't just mean how someone is raised (although that is sometimes part of it). I mean the effect the environment can have on how the brain is hardwired very early on.
In the womb, things happen that can affect how we develop. A surge of hormones here, a viral infection there, and we are not the same as we would be without these environmental factors.”
