I have nothing against homosexuality but I think its clearly not "natural" in a Darwinian sense. It doesn't allow for reproduction, and therefore has no longterm surivial value (in fact it has negative survival value).
Science that there is a biological reason for it means nothing to anyone, though. A religious person against it would say, "we are in a fallen state of sin, and that is a manifestation of sin that must be conquered. Some people may well be biologically inclined to be murderers or have trouble mentally in some other way with psychosis, personality disorders, kleptomania, etc. If you're a kleptomanic christian you can't be stealing and if you're predisposed to be a gay christian you can't be gay." So science won't get beyond intolerance, sorry.