Has anyone ever heard of the test where a lesbian was given daily doses of testostrone, in an effort to see how far she could be changed into a man?
When I saw anything of her last of her, she had grown more like a man features wise (brawd shoulders, facial hair, muscle mass) but she did not report any psychological changes. After 6 months, although I am unsure about that time scale.
Also, in the case where homosectual parent adopt children, the children do not necesarily turn out to be homosexual.
So there should be more factors involved than the environment one is raised in. Although I believe that would be the most prominent.