Reading some of the above answers showed a rather entertaining mix of beliefs concerning bisexuality, mostly just attacks on it vaguely disguised as definitions. I don't care about the fact that you can write well, it doesn't persuade me that I'm 'mentally ill' at all. Bisexuals, like me, are simply people capable of falling in love with people of either gender. It's a simple matter of love, and NOT a step towards being gay. I acknowledge the fact that there are a lot of people out there who claim to be bisexual when they're really straght/gay/lesbian, but the majority of these are attention seekers. I am NOT to be classed in this category; if I was an attention seeker, everyone would know. I haven't told more than two people in the whole world so far, excluding all the people reading this. And, contrary to popular opinion, bisexual people can hold down relationships with one person at a time. They don't find the need to run off and have sex with the first good looking person they meet. That person is a bigot, not a bisexual. Just because some bigots are bisexual doesn't mean that all bisexuals are bigots.
In conclusion, I'd like to say that bisexuality is a perfectly normal choice that, whether they like to admit it or not, almost 95% of the population of the world is sitting on.
I've always wanted children, ever since I can remember. I've fallen desperately in love with a girl, so deep that it hurts every time I see her. But I fantasize over men and prefer their bodies. I am bisexual - get over it.