I have the habit of converting lengthy comments into blog entries, so you'll have to get used to this.
Yesterday, somebody asked me why a lot of people equate bisexuality with homosexuality. I argued that homosexuality (same sex is hot) is just one part of bisexuality (both sexes are hot) with the other part being heterosexuality (opposite sex is hot). So, in a way, yes, bisexuality may be (arguably!) a form of homosexuality. After all, exclusivity is not implied in the term.
I think the bigger issue, though, is that some people think of bisexuality as an "impossibility" since you either like males or females, and can't genuinely like both. Even amongst self-identified homosexuals, there seems to be a prevailing notion that their former (or occurring) heterosexual feelings (ie. bisexual feelings) are stages of confusion or denial. And whilst it can certainly be confusing to a number of people, to call it "denial" is putting our fluid nature in a box. A very, very small box.
It's true, we probably don't actively choose who we find hot, but we're not predestined to fall into neat boxes, either. That's just sexual calvinism and it's not very intelligent.
I stand by many of our social scientists that bisexuality may actually be the default (?) and most natural form of human/mammalian sexuality. Most other animals are known to exhibit mixed sexual behaviour rather than a strict homosexual or heterosexual lifestyle, after all. Homophobia seems to be uniquely human.
I think humans are mostly just sexual beings: Only a very small percentage of the species is actually into pure androphilia (love of males) or pure gynephilia (love of females). This nature, however, can sometimes be superceded by our societal or self-constructed biases (or both), as evident in our race.
Related to all this is the equation of sexuality with gender. Like, if you're a man and you like other men, you have to be effeminate. Almost just as silly as sexual calvinism, but I shall bore you with that at another time.