I responded to you a couple of days ago but I fear the spam killer grabbed my post.

But the cliff notes as I remember them…

You are correct genes appear to play a part, but at least for now it looks like a small part.

You know we’ve already been through this, right?

Actually, twin studies DO suggest that something genetic is going on.

From NYT article on the Bailey study from the early 1990’s

“We found 52 percent of identical twin brothers of gay men also were gay, compared with 22 percent of fraternal twins, compared with 11 percent of genetically unrelated brothers,” said J. Michael Bailey, an assistant professor of psychology at Northwestern University in Evanston, “which is exactly the kind of pattern you would want to see if something genetic were going on.” By “unrelated,” Dr. Bailey was referring to brothers by adoption.

And from a Wiki article on the subject

“Twin studies give indications that genes may predispose some men to seek partners of the same sex. Hamer commented “From twin studies, we already know that half or more of the variability in sexual orientation is not inherited. Our studies try to pinpoint the genetic factors, not to negate the psychosocial factors.”[88] One common type of twin study compares the monozygotic (or identical) twins of people possessing a particular trait to the dizygotic (non-identical, or fraternal) twins of people possessing the trait. Bailey and Pillard (1991) in a study of gay twins found that 52% of monozygotic brothers and 22% of the dizygotic twins were concordant for homosexuality.[89] Bailey, Dunne and Martin (2000) used the Australian twin registry to obtain a sample of 4,901 twins.[90]”

True, we don’t know.

But…

Strong Clue #1: Identical twin studies show very low concordence for SSA.

This is an indicator that SSA is triggered (or not triggered) sometime after birth. This doesn’t mean that the prenatal environment isn’t important but a genetic/prenatal environment combo almost certainly isn’t the whole picture. For every environmental difference that babies experience in the womb, there are at least 100,000 differences they experience after birth. If you played the Vegas odds you’d have to guess it’s something that occurs after birth although probably at a very young age. My guess… first few months of life up to the first couple of years.

I absolutely agree with you, but the multiple factors you are talking about usually fall under one of the two general headings: Nature or Nurture 🙂