Yes, two years ago my son came out, at 18.
Julie -- Even though my son had liberal-minded parents who had always accepted gays (although we had no clue our son was gay), it was still hard for him to come out. It's much more accepted these days, but it's still hard for kids to come out. You couldn't live in a more gay-friendly area than we do, but my son only formally came out to his friends last month (even though they probably already knew, since a few people had probably already spread the word).
ETA. I have to add, I had known many kids who came out, and I supported them and thought nothing of it. But when it's your own kid, it's sometimes harder than one might think to come to terms with it, especially when it comes as a total shock. Nothing about my son was stereotypically gay, and no one knew or guessed, not even his close friends or his siblings. Just like any dreams we have for our children's futures (and very few of us don't burden our children with some of our own hopes and dreams for them), finding out your child is gay means radically altering your visions of their future lives, and it does add health concerns and societal worries that one doesn't have to consider with straight males.
I talked to a lot of people as I went through my personal journey with this, and very few people went "yipee!" when they discovered their child was gay, but most of them went through some kind of grieving process until they achieved complete acceptance, as did I.