I think that people are born with the propensity to be gay, some more than others, a friend who did psychology mentioned in passing that for women, it could be a testosterone imbalance when the foetus is developing. I remember this hazily so don't shoot me if I'm wrong
Well, from personal experience, Growing up, I always had a huge thing for women, posters on my wall were all female celebs, but it wasn't so much a sexual attraction but more of an admiration "i wish i could be her" kinda thing. I was involved with a guy for 7 years, but later broke up and got involved with a woman. I come from a very conservative society, where homosexuality is frowned upon, therefore, perhaps growing up, I just curbed my nature to fit in and not rock anyone's boat.
However, having been women now, sometimes i think i opened pandora's box. As a teen, Lust was generally towards men, now... its like i just look at women! I think its conditioning and environment that "enhances" my gayness. Well i don't really know if what im posting makes sense, but yeah...
I think people are born with the potential to be gay.. some more than others, and social factors, environmental conditioning and personal mindset can greatly influence it so that it "seems" that its the environment that makes people gay. Bottomline imho is that you cant create something that wasn't there in the first place.