Well, to the same effect, many christians (not all, but many) force their lifestyle on children as well. Before they are mature and educated enough to make a decision. I would say to a much greater extent. Someone else being gay does not affect you anymore than someone else being religious affects me.
It's not the same, because a parent teaching their child about religion is well within their rights as a parent. Gay activists, through public schools and the media, are forcing their views upon other people's children.