 Such remarks have led to Beauvoir being regarded as an originator of the sex/gender dichotomy, which became pivotal to feminist theorizing in the 1970s (see the entry:  feminist perspectives on sex and gender).  Standardly sex was seen as fixed by biology, and gender, as the social meanings attached to such biology, seen as historically and socially variable, and open to change. It is in this context that Beauvoir’s famous claim that “One is not born, but rather becomes, a woman”, is consistently quoted (1949 [1982: 295]). Nonetheless Beauvoir’s own position does not map onto this sex /gender distinction in a straightforward way (Sandford 2006, Lennon and Alsop 2019, cp 4). For her the data of biology, offered as facts, lack the fixity which later accounts sometimes took for granted. She shows herself aware of the way in which cultural myths and metaphors influence the telling of the biological story, even as she herself offers it to us. In pointing out the ideological influence on the descriptions of the active sperm and the passive egg (1949 [1982: 44] she anticipates the work of later writers (Martin 1987). Moreover she shows herself consistently aware of the possibilities which the biological data leave open to us, stressing alternatives to heterosexual reproduction throughout the biological realm, the incidence of hermaphrodism in human and other animals, and drawing attention in the animal kingdom to cases where care of the eggs and the young is done by both male and female animals. The consequence is that not even the biology of sexual difference is determined. 