[Moseley]

Myself, I’m of the part-genetic, part cultural persuasion.

This is of course a possibility. But if there were a genetic contribution to homosexuality, why is it not EXTINCT by now? By definition homosexuality reduces the rate at which homosexuals have children.

Yes, homosexuals can and do and have over human history had children. But by definition anyone carrying a homosexual predisposition as a gene would have LOWER rates of reproduction than heterosexuals.

That's by definition. That's why the activists can't wrap their head around. Homosexuality, by definition and by its nature, results in a reduced frequency of children. No, not zero. But at a distinctly lower frequency than heterosexuals.

So you have the unavoidable result that any genetic basis for homosexuality would already be extinct by now. (We have historical references going back at least 3,000 years. So 3,000 years is enough time for extinction of the gene.)

I’d like to point out that a lot of research has gone into trying to find genes that code for intelligence, with minimal success—it seems to be due to the outcome of the combination of a number of genes.

But again you are missing the fact that intelligence is essential for human life. It is part of the standard, original pattern. Without intelligence, there is no human being. So having the genetic basis spread throughout our entire genetic code is reasonable.

By contrast, there must be a CHANGE from the standard of heterosexuality to create a genetic basis for homosexuality. There had to be a genetic mutation at one particular place on Earth in one particular ethnic group at one particular point in time.

It isn’t inconceivable that a predisposition to homosexuality might be genetic, although there’s clearly a lot of acculturation going on in most cases (otherwise, why all the promotion?).

But if there is a genetic predisposition, why isn't the genetic basis extinct already?

That's the problem no one is thinking about.

A genetic predisposition has to BEGIN somewhere in human evolution. It did not just fall out of the clear blue sky.

And the genetic predisposition would have to be passed on to children or it would die out.

[Albion Wilde]

if there were a genetic contribution to homosexuality, why is it not EXTINCT by now? By definition homosexuality reduces the rate at which homosexuals have children.

Because of the social pressure to get married to the opposite sex mentioned above. Homosexuals who can function for a period of childbearing years in conventional marriages can still be promiscuous with men on the down-low; or divorce and be exclusively homo after having the kids. The rate of bisexuality for women is even higher than for men. Remember, it is not an on-off switch. It is an addiction to a certain type of sexual practice; but that doesn't make the other practices impossible, especially if their purpose suits an agenda of "fitting in" in society, congregation or business.

[Pearls Before Swine]

If predisposition is a result of a combination of genes which have other useful functions, and don’t predispose to homosexuality in other combinations, then I don’t see why it would be eliminated by evolution.

If it’s caused by a single gene, your argument is pretty good

[Svartalfiar]

But if there is a genetic predisposition, why isn't the genetic basis extinct already?

No, it wouldn't necessarily. There are many genetic conditions that result in failed offspring or infertility. Some are mutations, some are recessive genes that require rare combinations to occur. Even if a homosexual gene completely prevented children (gays still have normal sex sometimes), it can still make it through generations of genetic passing-on. Quick google search:

Genetic Causes of Female Infertility

Y chromosome infertility