Is it normal for parents to reject their gay sons and daughters?

Almost everyone I know who is gay has been rejected immediately when they came out. They came out before becoming financially independent, ended up nearly on the street, in all sorts of dysfunctional relationships and bottom-of-the-barrel careers.

I'm not thrilled about being gay myself, and I've slipped up about my sexuality once too many times, and I'm worrying that they're catching on and this situation is five minutes to critical. I've saved about 14 grand ever since I first realized I was gay at fifteen, so I'm fully ready to get out of here in a jiffy.

But is there a sort of psychological process essential to evolution that causes parents to reject their gay sons and daughters? Is this just a normal part of the way we have evolved, similar to universal repudiation of social ills like drugs and prostitution? I see it happen 100% with everyone I know of. I have NEVER seen ONE accepting parent or family member. I'm anticipating the worst, and am fully ready to make any compromise necessary to preserve the integrity and continued operation of my family unit (including making any scientifically sound attempts at changing my sexuality for them)...but I fear their reaction may be too sobering.