Speaking as a lesbian who is married (thank you Canada!) and is raising a child with my wife, we are happier than most straight couples I know! Obviously not everyone is the same, but that applies to straight marriages as well as any other type of consensual relationship. My daughter is loving, happy and accepting. When she sees 2 boys kissing, or we hang out with my transgendered friend, she doesn't think of them as weird, or freaks or anything bad.
Parents raise their children to become like them often, and if a gay person or a straight person is raising a kid to be accepting, they will be accepting. If the child is raised to be judgemental or discriminating, then chances are that they will be.
I support marriage and loving relationships for everyone. If two consenting adults love each other, then why can't they get married? That's just me though, thanks for the great list of comebacks, they are great!