Fitting Homosexuality Into Darwin

Over the past 10 years or so, movement homosexuals and those who support them, have been attempting to find a way to prove that homosexuality is not a choice. This has included a search for a gay gene, offerings of various theories as to brain function, and the general suggestion that no one would make such a choice when it creates such problems for those so choosing. Thus, the argument goes, homosexuality is natural and hard wired. So strident are believers in this conclusion that it is now considered unethical to "treat" homosexuals with a goal of moving them to the straight life.

But under a naturalistic or evolutionary paradigm, I have been unable to think how homosexuality fits in. Maybe there is a huge body of work on this, and I admit to not doing any additional research in preparation for this post. However, my substantial reading and study in this area over the past 40 years doesn't bring to mind any discussion of this idea.

As previously posted here, I believe that some homosexuals are born with a predisposition towards homosexuality. This would be in much the same way as some are born with predispositions to be substance abusers, be athletic champions, become diabetic, etc.

Under Darwin, one would expect that genetic variations which do not increase chances for survival and propagation would be less likely to be passed along to future children. Over time, these mutations would theoretically become so unlikely as to be at or near zero.

If we now add to the biological problems for continuation of this variation, the agreed upon social stigma, one would expect that the homosexual population would be decreasing over the centuries and would be non existent a long time ago.

How then does the homosexual variation continue? What natural advantage does it bring? How does it get passed along in the gene pool? Why, with the huge societal stigma, does homosexuality even continue as a social variation?

Finally, does this question give rise to another bigger question? Under Darwin, how have other so-called, hard-wired predispositions survived, such as substance abuse, schizophrenia, or Down Syndrome.