[Blarg]

But we have not measured the brains of all homosexuals, nor are we sure that such behavior cannot modify the brain or hormonal system, as happens with other environmental influences.

Btw, I count pollution and such as potential environmental modifiers, too. Perhaps acting on genetic predispositions/existing hormonal balances to help cause various diseases. All us milk drinkers and beef and chicken eaters are getting unprecedented levels of hormones that way, and we are getting pseudo-hormones through pollutants that already are showing the sperm count of human males has plunged in the last half century. They've also been indicated in frogs and fishes and lizards becoming hermaphroditic, or infertile, etc.

We don't know enough about genetics, chemistry, and the incredible number of ways they relate to each other in any single person or animal to really know what we're talking about when we talk about environmental influences on something as complex as human sexuality yet. Our science isn't there yet, a few studies with some measurements notwithstanding.

And we don't really know definitively how much and in exactly which ways social factors shape either the personality or the raw material of the brain and hormonal system, either. We just know that it does, and that new findings are turning up all the time. So it's way too early to say we've got any of this stuff really figured out.