Can't be married??? By who's law?

In my opinion... the laws of nature.

Then you have no basis, at all, in disallowing gays to be married, since homosexuality is well documented amongst animals (including a case of non-consensual homosexual necrophilia between two mallards). It's far from rare in animals, and it's far from rare in humans. I assure you, not a single gay person I know has chosen to be gay, given the ridicule and etc. that they have to deal with. (Not being gay, I can't speak in the first person, but I do ask gay friends that question, because I want to know.) Ergo, your "law" is not a "law" in the least bit.