OK, Raspewtin, I'll go over it again. You said that you are 75% CERTAIN that homosexuality is a personal social choice. You said that...(individuals who have a predisposition NOT to pro-create would be selected out. Thus if being gay was genetic, IMO by now, there would be no more gays.) You later say: (I can't think of how a homosexual preference would lead to reproductive advantage. I seriously doubt a breeding population could support a sub-population of homosexuals after several generations, since over time, they would contribute smaller and smaller amounts to the gene pool.)
Now instead of saying that I seriously doubt you are right I pointed out that it is not just the OBVIOUS viability of the individual that counts, but the viability of the individuals in variable, perhaps unanticipated circumstances, such as the case of sicle celled anemia where the presence of malaria confers greater survivability to carriers. There are examples I didn't mention and others did. Also, it is not just a matter of whether the individual breeds, but whether his sisters and brothers do, since they carry the same genes. It is possible that early man could best survive in small groups with slow reproductive growth due to low efficiency in resource acquisition, and that homosexuality acted as a break on growth. It's possible that homosexuality results from multiple alleles, that grade from hetero to bi to homo. There are lots of things that could guarantee survivability of a homosexual gene, likely ones we can't see.
Your premise that homoxesuality disappears because homosexuals don't have childern is doesn't hold water and shouldn't lead scientifically to a 75% certainty about anything.
I could be wrong, but I think your reasoning is not sustainable in the light of additional possibilities. In other words when we can account for facts in more than one way, we can't say that one way is right. I don't have to give a specific alternative, only demonstrate that alternatives exist. The issue is, however, open for debate. I don't think all the data is in by a long shot.
If you are really interested, you can check out the bonobo chimp, our closest relatives. Homosexuality is there in spades, I believe. It's kind of odd to talk about them choosing it.