"When a man and woman love each other very much, the man puts his penis into a woman's vagina, and that's how babies are made. Also sometimes men love men and so the man puts his penis into another man's anus, but this doesn't make babies. Alternatively they rub their penises together, which is called 'frottage'. Also, some people like to tie each other up and then pee on each other, though you should always ask permission from your partner before doing that. Also, sometimes people have sex for reasons other than love, such as for money, which is called 'prostitution', or for revenge, like when you saw mommy in bed with a man who wasn't daddy, which is called 'getting pay back for four long years of oppressive patriarchal dominance'."
Heh, that got kind of long.
Anyway, my point is that your job as a parent is to make things less confusing, not more. It's up to the individual parents how to do that. If homosexuality isn't a major issue in their kid's life, why make it one? I mean, I could make an argument about the importance of teaching your children about the hardships Irish immigrants in America went through, and why the Lucky Charms leprechaun is a horrible throw-back to extremely prejudiced attitudes towards the Irish. But try explaining that to a kid who just wants to eat the damn marshmallows.