Dont know about EVERYONE. A lot of people have what i would call bisexual potential, they could get off on doing it with both sexes, but few people really have the guts to admit and experiment with it. Really girlfriends, sometimes i wonder if you know what goes on in the heads of your man...
I am like 90% homo, with 10% hetero potential stuffed away there in the back of my mind. I could get turned on with a girl, and have done so before. But at the same time changing mindset to be thinking of girls also would sort of complicate my life more right now, and i dont need complications.
I think the terms homo, bi and hetero are, like someone said, in themselves crippling. We use them to limit ourselves and make the world a simpler, right/wrong kind of place. I hope that in the future human sexuality will not be cause for so much hipocrisy and alarm, and we can all just accept ourselves as the horny f***ers we are, without artificial limitations.