Getting back to the original Q about how human sexuality is determined: It has been scientifically proven that homosexuality is largely created in the womb. Males are supposed to have a flushing of certain chemicals in the both the first trimester and third trimester.

Sometimes, for whatever reason, this flushing does not occur with boys. And, girls may be flushed with those chemicals instead. This is largely considered to be what determines very strong homosexual characteristics, and are evident in early childhood.

Bi-sexuality is much more subjective. Environment has a big effect on the acceptance and comfort level on individuals. I do think that most people have considered the option, in one way or another, sometime in their lives. But a lot of factors come into play about whether or not they will ever seriously look into playing out those options.