It's an interesting question on a purely academic level, but what's always bothered me about the nature vs nurture debate on sexuality is the implication that the answer could have moral implications. If someone is born with a certain sexual preference then it is utterly pointless to try to change them, let alone condemn them; but if it's a result of imprinting at an early age then perhaps gays, sado-masochists and even pedophiles could be 'cured' someday. Maybe they should be forced to seek treatment.
I don't have an opinion either way but I am personally very happy to see that scientists are looking for a biological cause rather than a psychological one. If the only way for prudes to finally accept the sexually different is to say "well, they were born that way so there is nothing to be done." then I am all for it. I just hope that it doesn't backfire to "Well, we can't change them, so let's kill 'em!"