There isn’t one; there are many. Does it matter?
A new study involving hundreds of thousands of participants finds that homosexual behavior is about one-third genetic — and that many genes are involved, each having only a tiny effect. It even manages to single out a few: “rs34730029,” for example, increases the chance of having a same-sex experience by 0.4 percentage points. These genes might affect sex hormones and the sense of smell.
This is a breakthrough, but it won’t surprise anyone who’s been paying attention to developments in genetics. The one-third estimate is consistent with earlier, simpler studies on twins. And while making some sense out of humanity’s zillions of DNA bits is an impressive feat, countless previous studies have used these same methods to analyze other traits from schizophrenia to educational attainment — always with the upshot that lots of genes, each with a small effect, were at work. If you’re still captivated by the idea of a single, all-powerful “gay gene,” or for that matter an all-powerful gene for any behavioral trait, please drop it.
The more interesting questions are whether the causes of homosexuality have any political implications in this day and age, and whether it would make sense to try to stop research like this from happening.
In covering the study, the New York Times summarized its critics’ fears. To them, this is a Catch-22 where a result in either direction gives the bad guys — social conservatives — ammo:
One concern is that evidence that genes influence same-sex behavior could cause anti-gay activists to call for gene editing or embryo selection, even if that would be technically impossible. Another fear is that evidence that genes play only a partial role could embolden people who insist being gay is a choice and who advocate tactics like conversion therapy.
One of these is a worry from the future, the other one increasingly consigned to the past, but both are worth discussing.
The gene-selection dystopia is the bigger and scarier possibility, though I am not sure how many critics of homosexuality are also big fans of tinkering with human DNA. We can already create embryos in a tube, test their genes, and then implant the ones we like best. We already do it to prevent genetic diseases, in fact. But this just lets parents choose among a set of embryos they made; it doesn’t let them create a “designer baby” in detail. For that you’d need gene-editing technology.
Which also already exists, even if, practically speaking, it’s too error-prone to be worth the risk. Yet there’s no stopping its improvement: Even in the unlikely event that the U.S. banned gene-editing research, other countries (and rogue scientists) would proceed regardless.
The same, of course, is true of research on which genes cause homosexuality. If these authors hadn’t done this study, someone else would have soon enough, and the studies coming out 20 years from now will be even more extensive and precise, identifying far more of the specific genes at work. How would you possibly put an end to surveys and blood tests in an age when you can buy a DNA sequencer online?
Gene-editing technology plus detailed knowledge about which genes affect which traits: You do the math. Eventually it will almost certainly be possible, and perhaps legal in some countries eager to attract a new kind of birth tourism, to edit an embryo for whatever reason you want, including reducing the chance your kid will be attracted to members of the same sex. How often gene-editing actually happens will be a function of the cost of such services, the risks, and humanity’s desire for them at that point in time.
I don’t have any insightful observation to make or wonky policy to suggest here. I just don’t think we’re going to stop this over the long run, at least not completely, and I don’t think this single study will carry much responsibility for it when it happens.
So what about the more immediate concern, that the new study gives credibility to the idea that being gay is a “choice”?
For starters, its findings aren’t too relevant to that debate. The fact that homosexuality is only one-third genetic does not imply it’s mostly a choice. There are numerous theories positing biological mechanisms besides genes — prenatal hormones, germs, etc. Other parts of the environment that we don’t choose could also affect our sexuality. The study did find that occasional experimentation with same-sex partners, as opposed to a consistent preference for them, overlaps genetically with the personality trait of openness, but I don’t think anyone doubted that was a choice to begin with.
More to the point: Yes, it’s true that whether homosexuality is a choice could have political relevance in a country trying to decide whether to ban it or discourage it. In theory, such policies will be more effective and less cruel when they regulate behaviors and tendencies that people can easily change.
But at least among the Western audience most attuned to this research — which is based on British and American samples — that debate is more or less over. Here in the U.S., the Supreme Court requires state governments to actively recognize gay marriages, and a growing majority of the public supports such recognition. (For whatever it’s worth, I am part of that majority.) Right now the legal action is on the question of when private businesses can be forced to participate in gay couples’ wedding ceremonies.
I don’t see decades’ worth of increasing acceptance of homosexuality disappearing just because this trait, like pretty much all human traits, is only partly genetic. And as for conversion therapy, frankly, while I’ve seen no evidence it works, if an adult wants to try to change his sexuality or learn not to act on it — hey, knock yourself out.
Interestingly, one of the study’s authors pitches his research as the opposite of a Catch-22 for the Left, a situation where both the environmental and the genetic component should somehow help to normalize homosexuality. “I hope that the science can be used to educate people a little bit more about how natural and normal same-sex behavior is,” he told the NYT. “It’s written into our genes and it’s part of our environment. This is part of our species and it’s part of who we are.”
Whatever you make of that as an argument, it’s no coincidence that the study’s authors are ready with spin like this for the press. One reason they did this research is that if they didn’t, another, less careful team might have done it first, without all the consultations with LGBT activist groups that the paper touts to shield itself from the mob.
Anyway. We are rapidly learning more about human nature and human variation, and the discoveries will only keep coming. Some of that knowledge will help us live longer and fight disease; some of it will make us more tolerant of people we don’t understand; some of it could be used for evil purposes. And all of it, heaven help us, is too fascinating to ignore.