I'm almost 99.9% sure that this is the answer to the question posed. homosexual people are in heterosexual relationships and producing children. One could ask, well, does that mean every homosexual offspring has at least one (1) homosexual parent? Probably not, but I'm willing to bet the number is at least statistically significant and genetics makes up the other large portion.
what if gay marriage and adoption lead to reduced genetic fitness for Gay folks? No longer a need to be in the closet so no beards no kids from the beards -> reduced allele frequency -> no more gays. Gay liberation may lead to the extinction of Gay folks.
yeah, it's ironic. If anti-homosexual people want homosexuals to go away, wouldn't it be smart to stop forcing them into heterosexual relationships and reproducing?