If the immutable character of sex is contested, perhaps this construct called "sex" is as culturally constructed as gender; indeed, perhaps it was always already gender, with the consequence that the distinction between sex and gender turns out to be no distinction at all.
It would make no sense, then, to define gender as the cultural interpretation of sex, if sex itself is a gendered category.
Revealing the natural body as already clothed, and nature's surface as cultural invention, Simone de Beauvoir gives us a potentially radical understanding of gender.
Her vision of the body as a field of cultural possibilities makes some of the work of refashioning culture as mundane as our bodily selves. Females have two X chromosomes (XX) - Males have one of each (XY).
To become a gender means both to submit to a cultural situation and to create one, and this view of gender as a dialectic of recovery and invention grants the possibility of autonomy within corporeal life that has few if any parallels in gender theory. The body becomes a choice, a mode of enacting and reenacting received gender norms which surface as so many styles of the flesh.