I honestly think a lot of the opposition is because most people still think it's a choice.
-For example, in that Alaska demonstration thread (
here) if you follow the picture link, there is a sign at the bottom right of the 5th picture down... "I was born Asian, You choose to be gay."
-When the staunchly anti-gay people refer to it, they often use the term "lifestyle choice."
-My officemate's daughter at work has several gay friends, and she often says her husband strongly believes it's a choice and that is why he doesn't like them.
I'm sure I could come up with many more examples, but I see it everywhere and I'm convinced it's the mainstream view.
That said, I believe there are two things that could change the thinking in this country. One is for most people to actually know a gay/trans person and realize "Hey, wow, they're just like us". Another is for there to be proof of a physical cause from a reputable source. As long as they go along thinking we're just bad people, they will feel justified in shunning us perverts and devil-worshippers. (yeah, that last part was tongue in cheek

)