The fact that there is a biological determinant in homosexuality has been demonstrated by studies on the brain functions of homosexual versus non-homsexual males.
The fact that homosexuality becomes so prevalent in certain societies, i.e. among the Romans of the late Republic and the Early Empire, some of the Ancient Greeks and the Ottoman Turks, and the fact that their recent descendants did not express this trait, indicates that widespread homosexual practises have a behavioral and societal component, as well as a biological one.
If we allow homosexual behavior to be accepted as merely one more alternative and accepted lifestyle, we are running the risk of having modern America degenerate into a sexual equivalent of Ancient Rome, Ancient Greece, or the Turkish Empire. Not very savory models to emulate.
What studies are those?
When I can no longer trust my son in the care of a Catholic priest, and when I am told I'm a horrible person for not OK'ing a gay man's taking my sons out on overnight camping trips, it's already happened. And it's not savory. At all.