So kulturkampf...

[derrida]

Maybe I misread your response, Kulturkampf but it seems to me that the examples you raise give credence to the idea that sexualities are at least partially socially constructed. If the lack of a homosexual sex taboo results in an apparent increase in homosexual behavior we can conclude that the exhibition (if not the genesis) of such behavior is influenced in part by social norms. (If you are interested I can look up scholarly articles for you regarding societies that are almost exclusively homosexual save for procreative sex)