Laws of Attraction

What is it that makes us attracted to someone? Or, better phrased, why is there attraction at all? One could argue, I suppose, that it's for the survival of the species. But that answer seems to fall short. If attraction exists for the survial of the species, then why are gay people attracted to members of the same sex? Or (for you homophobes out there), why are we attracted to certain members of the opposite sex, rather than all of them? "For the survival of the species" seems to me to be a particularly weak answer when one considers the overprocreation that occurs. All other types of plant and animal life eventually reach an equilibrium with their environment. Humans don't.
A further question would be why aren't we all attracted to the same type of person? Why do some cultures value obesity vs a skinny waistline? Why do some guys prefer redheads to blondes, or some women prefer brown eyes to blue? Is it something in our genes? Again, I'd say probably not, because I think the notion of what makes someone attractive differs even between parents and their children.
Attraction is a nuisance to me. There is so much in this world that I want to see and do and learn, and I know it will take a putzload of time and money; so much so that I will not have enough of either to spend to try to catch the eye of that "special someone." And yet I do. Every time I think I can swear off women, another comes along to catch my eye. And it's not even that I wind up dating these girls, but it's the very fact that I even want to in the first place. Is it an addiction of some sort? Is it akin to smoking, where we know full well that we should stop, and we know we can't afford it, but nevertheless we are compelled to it simply upon seeing a cigarette?
It seems to me that with members of the opposite sex, perhaps moreso than anything else, we lose our free will, in a sense. Let use speeding as a counter-example. I drive fast. Too fast, probably, by even my own standards, but definitely over the legal limit. After my last speeding ticket, I tried to slow down. And I did, for a time, succeed in obeying the limit (much to the presumed irritation of the drivers behind me.) But as time passed, I've gradually sunk back into my old ways, and I have a daily struggle to not speed again. But with women, it seems, there is no "gradually." I can swear them off for the sake of a peaceful, less stressful, more affordable life (at least until I get myself better situated), and turn around not FIVE MINUTES LATER and think "Damn, who's that? She looks good!" It's an impulse! I'd say an instinct, but again, I don't think it is instinctual, or we'd be that way for all and not just for some. I don't know what it is, but it's irritating. I'd like to be able to just turn my attraction off for a few years. Get myself back in school, get my finances squared away and stuff paid off, and then go "Damn, she looks good!"