I agree that there is little heroic about coming out as gay in today’s society, but I did find this aspect of the Jason Collins story fascinating:

He’s my twin, eight minutes older. We live only a few miles apart on the west side of L.A. But while most of our conversations are quick and light, this one was different.

…This announcement will be surprising to some people. I already anticipate the questions: “Are you the gay twin or the straight one?” This is uncharted territory, and no one can predict how it will play out. It’s a big deal — but it’s also not a big deal. When the media crush is over, Jason will have the strength to deal with whatever challenges come from being openly gay.

One of the more contentious intersections of science and society is the question of whether homosexuals are born, or made. Both gay people and those who think them sinners have a political stake in the answer, and one of the most compelling arguments in favor of gay marriage has been that if you don’t have a “choice” to be attracted to the opposite sex, then it’s unfair to not be allowed the benefits of matrimony. Those who condemn homosexual behavior, whether out of simple disgust or for religious reasons, have to believe that gay people, indeed, do have a choice, and are simply being willfully immoral.

Now it happens that I personally believe that gays are born that way, because I am absolutely certain that I was born straight. No one ever taught me to be repelled by the thought of having sexual relations with another man, or schooled me in the obvious appeal of the female form in all its aspects, but that’s how I roll and always have ever since I’ve had any sexual awareness whatsoever. I can imagine no form of therapy (at least not involving hormonal treatments or other chemical interventions) that would somehow persuade me to change my heterosexual ways, and I would imagine that homosexuals feel just as constrained by their innate nature.

For those who, like me, accept that gay people are born, not made, there have been a number of theories over the years how it occurs. Some think it’s genetic, while others think that it may have something to do with the prenatal environment. But here we have two people who share the same genetic code, and shared the same womb at the same time, one (now) reportedly gay and the other reportedly straight, which would seem to be a problem for both theories. Interestingly (and I only learned this while researching this piece) this is not a new problem. It turns out, at least if this study is to be believed, that if one identical twin is homosexual, it’s a flip of the coin that the other one will be, whereas it’s about one in five for fraternal twins (that is, same womb, but different DNA). This would seem to be at least some evidence for the genetic theory, but certainly not dispositive.

One recent theory to explain this is based not on genetics per se but on epigenetics, in which heritable phenotypical changes can occur without an actual alteration of the gene sequence. Unfortunately for the theory, though:

…so far the theory “is not supported by any data.”

Indeed, Andrea Ciani, an evolutionary psychologist at the University of Padova, thinks that a variety of factors, including genes and epigenetics, influence sexual orientation. “It’s a little bit vain to think we’ll find the answer to homosexuality as a whole.”

Which is just as well, because I really didn’t want to get into those particular biological weeds. And to the degree that it’s genetic, it’s unlikely that it’s a single gene, because it doesn’t seem to be a very evolutionarily useful one. It’s more likely some complex of genes, each of which is useful on its own, but when combined, results in the person being gay.

Anyway, I have a more parsimonious explanation. Whether from gene or womb, most people (like me) are born straight, a few are born who wouldn’t do it with the opposite sex on a bet, and some (perhaps a lot) are born in between and really do have a choice. That is, they are bisexual. My guess would be that it’s a skewed distribution toward heterosexuality, with a long thin tail of homosexuals, but a big bulge on the heterosexual side of the scale of folks who can go either way. That is, they are to one degree or another bisexual.

My theory would explain why some of the most vociferous opponents of homosexuality often (more often than one might have guessed) turn out to be attracted to the same sex — they have a choice, and they feel morally superior to those upon whom they project their own bisexual orientation, and thus assume that people who don’t uphold their own standards of morality are merely weak-willed. These would also be the people who really could be counseled to go straight for religious reasons — they really had been influenced by their postbirth environment, and were capable of going the other way.

So this might explain the twin conundrum as well. The twins who are both homosexual either were born homosexual or were born bi and both chose homosexuality. The ones where only one twin had that trait (as with the Collins brothers) were born bi, and made different choices. I know that if I were heterosexual with an identical twin, I would find it mind blowing to be told he was gay, because then I would be wondering why I wasn’t. But in Jason’s brother’s case, maybe he’s thinking: “Well, I decided to do the marriage-to-a-woman-and-have-kids thing, but I can see his point of view.”

In any event, the mystery continues.