I believe a lot of it is to do with upbringing and nurture rather than just nature yes.

I am sure some people are born gay and cannot be any other way. Likewise I am sure many more people are now gay because of the way society views homosexuality as an alternative option to explore.

I believe under the right circumstances, with the right background history and every single one of us could be made to have attraction to the opposite sex.

All of us are modelled and moulded by life experience. I think very little, if any is preordained from birth.