Structuralist theories of gender or sex are generally based on, or attempt to demonstrate, a relationship that is expressed in terms of the structural formula: men are to culture what women are to nature, or men are to women what culture is to nature. In continuity with the former functionalist approaches, which saw gender difference as a consequence of the biological particularities of each sex, the structuralist approach attempts to demonstrate the universality of the relationship as a consequence of the prohibition of incest (Lévi-Strauss's exchange theory) or the superiority of the social value of “culture” over that of “nature” (Ortner's theory). Later poststructuralist research has, however, shown that gender is largely a matter of performance and the consequence of social and cultural constructions of sex.