Biology dooms the Defense of Marriage Act.
Once again, other societies are more sophisticated about this than we are. In the Dominican Republic, a girl whose genitals change late is called a guevedoche--"penis at 12." Among the Sambia of Papua New Guinea, she (he) is a kwol-aatmo: "Female thing turning into male." Among the Americans, though, there is a very small number of terms to cover a vast array of gender ambiguities. Instead, we have the knife and the law. Like the medieval villagers who tried and hanged a cock because it laid an egg, Americans think they can trim or legislate away the polymorphous obstinacy of nature. They're wrong. There's the cock, and there's the egg. Plain as the genitalia under your belly button, if you have eyes to see.
David Berreby, author of Us and Them: The Science of Identity, has been a Slate contributor since 1996.