RSS feed for entries


Gay gene: it’s not what you think –part 1

This article in the Beeb set me off: The evolutionary puzzle of homosexuality. The idea being that gay people have fewer children which puts them at a selective disadvantage which means the gene ought to die out.

It’s a gender difference. Must be genetic.

This sort of thing drives me nuts. Who said there’s a gene? They’ve never managed to find one yet. Probably for the obvious reason that there have to be hundreds for any complex trait. That’s clear to some people. From the article, “Dr William Byne, editor-in-chief of the journal LGBT Health, believes sexuality may well be inborn, but thinks it could be more complicated than some scientists believe.” (He’s too polite.)

Who said the genetic traits have anything to do with desire? Genes code for biological traits; how those manifest in social interactions is not genetic.

Who said that in humans having flocks of kids is the ticket to success? It reminds me of how people agonized over the many children poor people had. The rich would be swamped! And yet, oddly enough, the rich survived just fine, thank you. The whole approach is so wrong it has no chance of ending up right. Garbage in, garbage out.

And it continues.

“The genes that code for homosexuality do other things too.” If those things confer an advantage on the reproducing members of the species, then the trait should survive. That makes perfect sense. So do they stop there? Nooo.

There are two or more ways this might happen. One possibility is that the allele confers a psychological trait that makes [each sex more attractive to the other.] … “We know that women tend to like more feminine behavioural features and facial features in their men.

Who’s “we,” kemosabe? That’s bullshit, unless you define the non-gorilla look as “feminine.” And if you do, it exposes your assumptions but they have no actual explanatory power regarding mutual attraction between any gays or straights who aren’t you.

Another way a “gay allele” might be able to compensate for a reproductive deficit is by having the converse effect in the opposite sex. For example, an allele which makes the bearer attracted to men has an obvious reproductive advantage to women. If it appears in a man’s genetic code it will code for same-sex attraction, but so long as this happens rarely the allele still has a net evolutionary benefit.

You’d think if that was much of a factor there’d also be a selective advantage for men who wanted to be attractive to women. Instead we have whole societies geared to caging women instead. That, believe me, is the opposite of attractive.

Another one that makes no sense:

Paul Vasey’s research in Samoa has focused on … [t]he idea is that gay people compensate for their lack of children by promoting the reproductive fitness of brothers or sisters…. Sceptics have pointed out that since on average people share just 25% of their genetic code with these relatives, they would need to compensate for every child they don’t have themselves with two nieces or nephews that wouldn’t otherwise have existed.

Two extra surviving children for every gay relative would be quite a remarkable pattern. But nobody’s remarked on it at a population level. The occasional individual might have that effect, but that wouldn’t be enough for a population-level propagation of “gay genes” which is what the kin selection theory postulates.

Gay people do have children.

Finally, something that is indeed a way to pass on gay genes. However, I don’t remember seeing results showing a much higher incidence of homosexuality in the biological children of gay people. That would support the point that “gay genes” probably don’t code for gayness but for something else.

So there’s a whole string of obvious indications that there is no gay gene, singular, and that the primary functions of gay genes, plural, is something other than homosexuality. And yet the take-home message in popular media is “Gee whiz. This is so hard to fit into a story about men chasing after women for sex. How is that possible?”

Next post: some promising ideas that might actually bear some relation to reality.