Georgiansilver, sorry, but science has already shown the effects of prenatal hormones on masculinity/femininity, including external genitalia and internal sexual preference. Environment *after* birth, as in rearing, has nothing to do with it. This is not, in human biology circles, a matter of opinion any more.

And the pregnant woman doesn't have complete conscious control over her uterine environment - if there are twins, if there are stressors, if there are other genetic factors that lead to changes in sensitivity to or production of various proteins, there will be changes in the degree to which the embryo will be masculinized (if you leave it alone, as in no masculinizing hormones, it grows into something that looks like a girl no matter what the chromosomes say). It doesn't take the addition of feminizing hormones to make a female. And the womb may be completely normal and the embryo itself have a greater or lesser than usual hormonal receptivity or production.

And if what is a sin is homosexual behavior, then either the gay kids have to behave counter to their nature, or they will sin. That's not very fair to the poor gay kids. And being unfair to gays sounds awfully like bigotry, to me.

Gay is going to turn into the same thing as left-handed - Most people prefer to sleep with the other, some will do either but have a preference either way (mostly other), and some really only like the same. Remember, there has to be variation so that nature has something to select from. And you don't have a gene for "being gay" - you have that preference for women is part of being male, and some women are a little over-masculinized in utero, and are formed with a few male characteristics. One of these might be being turned on by women. Likewise, some men may be under-masculinized during formation, and retain the default preference for desiring men. Believing that being at the tail of the distribution is somehow "evil" (sin is evil, isn't it? I wasn't raised in any religion so my book-learning may be off) was exactly what superstition used to hold about left-handed people.

Before she got to be a Holocaust survivor, Mom got to spend several school years with her left hand tied behind her back.... I am reminded of a song:

But these are more enlightened days
No room for all these savage ways
Leave them, let them go...