Gayle Rubin, political economy of sex quotes

Sex is sex, but what counts as sex is equally culturally determined and obtained. Every society also has a sex/gender system – a set of arrangements by which the biological raw material of human sex and procreation is shaped by human, social intervention and satisfied in a conventional manner, no matter how bizarre some of the conventions may be.

taboo against the sameness of men and women, a taboo dividing the sexes into two mutually exclusive categories, a taboo which exacerbates the biological differences between the sexes and thereby creates gender. The division of labor can also be seen as a taboo against sexual arrangements other than those containing at least one man and one woman, thereby enjoining heterosexual marriag