I happen to know a lesbian couple that have a daughter who is 12 and is very confused about what's right or wrong. Even after being told that there is no right or wrong, she still looks at her mom's and thinks that this how her life should be. So, I think it can have a negative effect.
Pueberty is a tough and confusing time for all kids, and perhaps it can be harder for kids with gay parents. But, there's also the kid who's dad gets drunk and beats up mom everynight or the mom who's having an affair with the gardener....etc, etc. I think those kids are much less likely to have their parents sit down and explain to them how and why their family is different than most. Gay families are almost obligated to discuss intimate relationships, in a way heterosexual families generally aren't... and often don't.
Is that a bad thing? Actually, maybe it's not. How messed up are most young people about sex these days? It's become almost taboo for parents to talk about inimate relationships and sex with their kids. Kids are left to "figure it out" on their own. If they are told anything usually it's of ideals their parents may not even live up to, let alone people their own age. Many people get so concerned with what others might think that they neglect honesty with the ones they love, even themselves.
These days families are so different and face so many challenges just to stay together, that I don't believe the privledge to turn away potentially caring, loving parents exists any more. The traditional family is quickly becoming a myth in this days world and it's not going to change back, something new must be born an nurtured. I don't think we can afford to be so picky, as to blindly refuse gay families from raising children. Personally, I'm more concerned with pedophiles, rapists, murderers, exploiters, etc. being able to raise families than I ever could be about homosexual, interracial, handicapped, or underprivleged couples having children. It seems much more productive to be honest with ourselves and work on developing new traditions and ideas of family, than to sit around and mourn and glorify the past, saying "things were better when...". Why not value a family based on how loving, harmonious, and supportive it is; rather than the characteristics of it's individual members?
Many people say, "but we have so many problems already, why add to them?"
But it's already there, homosexuality is about as likely to go away as pre-marital sex. I think that acknowleding gay families may well be a path to resolving some of these challenges facing society.
As far as kids getting teased in school goes, isn't there always something? I went to a predominately "white" school and I got ruthlessly teased for being "too white". Go figure.
/end rant :-)
Oh, and yes the original "gay guys in london" were idiots to post something like that here. But, unfortunately, idiots seem to come in all forms.