Why are people homosexual?

I was raised around heterosexuals…
That’s where us gay people come from—you heterosexuals.
–Ellen DeGeneres

Determining why some people are homosexual is impossible, but most self-described gays argue that their sexual identity was clear to them at a young age, and that they had NO choice in determining their sexual attraction.

Furthermore, categorizing someone by one sexual identity—homosexual, bisexual or heterosexual—is wrong because many people float on a continuum somewhere between straight and gay.