Essentialist assumptions are central to traditional ways of thinking about sexuality, both in common-sense knowledge and in theory. Until relatively recently most writers on sex saw it as an irresistible natural energy barely held in check by a thin crust of civilization. This was foundational for the pioneers of Sexology. Richard von Krafft-Ebing at the end of the nineteenth century saw sexuality as an all-powerful instinct which demands fulfilment against the claims of morals, belief and social order. Such views assume a pressure-cooker view of sexuality, with sex providing a basic ‘biological mandate’ which presses against and must be restrained by the cultural matrix (Gagnon and Simon 1974). It takes many forms. For many, sexuality represented threat and fear. ‘Sex’, as the anthropologist Malinowski put it, ‘really is dangerous’, the source of most human trouble from Adam and Eve onwards (Malinowski 1963: 120, 127). Liberatory theorists such as Wilhelm Reich and Herbert Marcuse tended to see sex as a beneficent force which was repressed by a corrupt civilization. Sociobiologists or evolutionary psychologists see all social forms as rooted in our evolutionary origins, encoded in the DNA (Weeks 2009a: 20). The basic mechanism, in the words of Richard Dawkins (1978: 7), was ‘the fundamental law of gene selfishness’.