What Causes Homosexuality?

A recent discussion in one of this blog’s comboxes veered off into the old nature-or-nurture/chicken-or-egg question about homosexuality.

The question: Is same-sex attraction the result of the individual’s genetic make-up, or it is the result of the environment in which they were raised?

Based entirely on a crude anthropology, I would guess that there must be a genetic component to homosexuality. Why else would same-sex attraction show up in most, if not all, societies and epochs of recorded history? The ways in which children are raised vary quite a bit from one time in history — and one culture or society — to the next.

So far as I know there is no way of ascertaining if certain cultures or methods of child-rearing have historically resulted in a higher proportion of homosexuals among their citizens. But it does seem — again, this is crude anthropology — to be pretty much ubiquitous.

That raises the question: Is there a “gay” gene somewhere on our chromosomes, like the brca genes that predispose people to breast cancer? The answer, at least for now, is that no one knows.

What we do know is — like my “anthropological” assessment — guesswork based on derivation. Perhaps the most interesting guesswork in this field comes from the so-called “twin studies.”

When I did a quick google, I found that there is more than one study attempting to correlate same-sex attraction with heredity by looking at identical/fraternal/non-twins . It turns out that these studies seem to indicate that there may be a genetic component in same-sex attraction, but it does not appear to be definitive.

Of course, there’s no way to know what this genetic component might be. Is it one gene, or two, or a combination of genes? It’s possible, say, that identical twins who are both homosexual might have inherited a combination of genes that made this outcome certain for them, while other pairs of identical twins where one is homosexual and the other is not might only have inherited one or two genes of this same combination, thus injecting the factor of environment into their sexual fates.

On the other hand, it made be that there is a set of inheritable factors that predispose a person toward homosexuality, but that same sex attraction develops only when this genetic make-up coincides with an environment that pushes the individual in this direction.

Another factor that some of the scientists who did these studies have raised is the environment in the womb. How did the hormonal input to the baby from the mother affect its development? Perhaps the “environment” in question is not so much psycho-social as it is biological.

All this is to say that we don’t know what conditions or factors lead people to experience same-sex attraction as a definitive sexual orientation.

I have seen, based entirely on being around gay men, that there are individuals who, though they experience same-sex attraction and define themselves (at least internally) as homosexual, are quite capable of functioning sexually as heterosexuals. They can and do marry women and hide their homosexuality. On the other hand, I have known gay men who simply could not do this. Their same-sex attraction was so profound that it precluded them even attempting to marry and “pass” as heterosexual.

I only mention this because it raises, at least to me, the thought that same-sex attraction may not be an all or nothing orientation for many people. It may, in fact, be more a matter of degree, at least for some.

None of the things I’ve mentioned here affect the arguments for preserving traditional marriage. I don’t see supporting traditional marriage as a denial of either the reality or the humanity of gay people.

It is just simply that men and women together are the people who create other people. No matter how much sympathy I have for gay people, no matter how completely I agree with many of their concerns, the fact is that homosexual unions are sterile. They do not make other people.

I am well aware that many homosexuals have resorted to manipulations of biology to have children. But these manipulations lead directly to the exploitation and commodification of both women and human life. They are, in themselves, misogynistic and evil.

Gay sex does not make people. Traditional marriage between a man and woman produces children and is the best cradle for nurturing those children to responsible and productive adults who can have children of their own and nurture them. Redefining marriage in strictly social terms that ignore this basic function of marriage is destructive to society as a whole. I am certain that gay marriage is the road to nowhere for our society.

On the other hand, I am equally certain that homosexuality is a fact of human existence. I do not think that we can set aside the reality of homosexuality, or the just claims for civil and human rights of gay people.

You can find one of the studies Gay is Not All in the Genes which was published in Science in 2008. I chose it because of the reputation of the publication and its relatively recent origin. There are many other studies out there, if you want to look.