[wtbob]

> What about marriage makes it specifically require a man and a woman?

Is that a serious question? What do you think marriage is, State recognition that two people want to have sex exclusively? Why does it even make sense to have State recognition of a sexual relationship? It really doesn't.

Now, I don't think it makes particular sense to have the State recognise sexual relationships which may produce children, because there's no real need for it too: modern paternity testing can easily solve the actual problem civil marriage addresses.

As for the rest, why should those civil benefits be limited to people in a sexual relationship? Why should I be able to put my brother on my insurance? Why shouldn't a fraternity be able to form a civil union if they wish?

What possible benefits does civil marriage confer that should be restricted to two people who have sex, but not restricted to two people who might produce children?