"Why can't a woman be more like a man?" asks Henry Higgins in "My Fair Lady." Women might point out that, since too many men seem to trust a mysterious toilet paper fairy to change out the forlorn tube of cardboard, it makes more sense to ask: "Why can't a man be more like a woman?"

But regardless of how we ask it, the question is a good one: Why can't members of the sexes be more alike? Why do so many irritating differences persist? Feminists' answer has been: cultural and structural sexism. Societies train women to take second fiddle to men in work and relationships — and then punish them for trying to break out of their assigned roles. No, say traditional conservatives: Women and men are different, and cultures reflect those differences.

The conservatives may now be getting some support from a surprising source: transgender men.