 Fausto-Sterling has argued that this ‘two-sex model’ isn’t straightforward either (1993b; 2000a; 2000b). Based on a meta-study of empirical medical research, she estimates that 1.7% of population fail to neatly fall within the usual sex classifications possessing various combinations of different sex characteristics (Fausto-Sterling 2000a, 20). In her earlier work, she claimed that intersex individuals make up (at least) three further sex classes: ‘herms’ who possess one testis and one ovary; ‘merms’ who possess testes, some aspects of female genitalia but no ovaries; and ‘ferms’ who have ovaries, some aspects of male genitalia but no testes (Fausto-Sterling 1993b, 21). (In her [2000a], Fausto-Sterling notes that these labels were put forward tongue–in–cheek.) Recognition of intersex people suggests that feminists (and society at large) are wrong to think that humans are either female or male.