NO I don't think they fight gay rights because they feel threatened.
It would not effect christians if science proved there was a gay gene. God is still God, no matter what science says.
There are as many intelligent christians as there are intelligent atheists. The reverse is also true (just as many idiotic christians as idiotic atheists).
It takes all kinds. And religion has nothing to do with the belief in God or Jesus. IMO
A better question is why are christians surprised that no one believes us about biblical prophecy beginning to be fulfilled when even the bible says "even the very elect will be deceived" ??