 However, the sex/gender distinction, also known as the Standard Model of Sex/Gender, is criticized by feminists who believe that there is undue emphasis placed on sex being a biological aspect, something that is fixed, natural, unchanging, and consisting of a male/female dichotomy.They believe the distinction fails to recognize anything outside the strictly male/female dichotomy and that it creates a barrier between those that fit as 'usual' and those that are 'unusual'.In order to prove that sex is not only limited to two categories Anne Fausto-Sterling's "Sexing the Body" addresses the birth of children who are intersex.