Roger N. Lancaster provides the definitive rebuttal of evolutionary just-so stories about men, women, and the nature of desire in this spirited exposé of the heterosexual fables that pervade popular culture, from prime-time sitcoms to scientific theories about the so-called gay gene. Lancaster links the recent resurgence of biological explanations for gender norms, sexual desires, and human nature in general with the current pitched battles over sexual politics. Ideas about a "hardwired" and immutable human nature are circulating at a pivotal moment in human history, he argues, one in which dramatic changes in gender roles and an unprecedented normalization of lesbian and gay relationships are challenging received notions and commonly held convictions on every front.