Well, here's my 2 cents.
I agree that the parents are allowed to make the rules for their own home, according to their own standards and beliefs. On the other hand, not all rules are good rules, and there are times in our lives when as human beings we're obliged to break the rules because we believe they're wrong. This often happens with young people because they're at that stage in their lives where they're trying to figure out what's right and what's not for themselves, and they need to follow their own mind to do that. They not only will break the rules and make mistakes, but they NEED to break the rules and to make mistakes, to learn. So any parent that thinks he/she can lay down the rules and expect their teenage children to always follow them is an idiot.
My other point is that it's interesting, here, that so many of the comments seem to imply that there is only one right way to respond to such a circumstance. But there isn't. We each can think about what we believe would be the correct responce to our child's homosexuality, and that's good, but we're all different people, and we're all going to have to respond a little differently in real life to something like this because we are all different.
I guess my point is that the parents are in a learning process, too. And just as the kid had to make his choices and deal with the consequences, so do the parents. If, as a an individual and as a parent, I'm going to participate in religiously based sexual bigotry, then I'm going to have to pay the consequences for that decision if my child should end up being homosexual. I may lose my relationship with my child because of my choices. My child may end up dead to suicide or homelessness because I chose my sexual bigotry over their well-being. This sort of thing happens in the real world.
No matter who we are, there are consequences for the choices we make. And we'll all make some wrong choices. That's inevitable. So we can either learn to be forgiving toward each other when we and other people make what we believe to be wrong choices, and when the choices of other people cause us harm, or we can end up living all alone in our own hatred, resentment, and stubborn self-righteousness.
The choice is ours, as usual.
As to the comments for and against conservative Christianity and it's role in this particular scenario, I can certainly understand the sentiments. People like Falwell make a handsome living preaching hate and bigotry in Jesus' name. Justifying hatred for people who have hate in their hearts and don't want to give it up will always be profitable. But in the end every bigot is his own responsibility. People like Falwell don't get a dime from anyone against their will. He's really just a parasite, feeding off the hatred and bigotry that already exists in people, by telling them it's OK to be that way, and that God is a bigot, too.
So the real responsibility lies with each of us as individuals. Sexual and religious bigotry continue to exist because of us, not because of Jerry Falwell or Pat Robertson or any of the other professional hate-mongers out there. And only we can put a stop to it. The moment we're willing to let go of such hatred and bigotry within ourselves, the Jerry Falwells and Pat Robertsons will vanish. Christianity didn't create them, our own ignorance and prejudice did. And when we're willing to let go of our ignorance and prejudice, they will vanish, while Christianity will remain.