"„In the late twentieth century, after all, we are ourselves literally embodied writing technologies. That is part of the implosion of gender in sex and language, in biology and syntax, enabled by Western technoscience.“ Donna J. Haraway (1991), Simians, Cyborgs and Women. The Reinvention of Nature. London: Free Association Books, p. 128. These thoughts were the stimulus for this paper’s effort to treat the notions of ‘sex’, ‘gender’ and ‘identity’ through the controversial points of view, emerged among the feminist writings of the 1970s, the historians and psychoanalysts of the 1980s.While post-stucturalists like J. Butler are passing from gender denaturalization to the undoing of gender, brain scientists speak about a potential underestimation of innate biology at its equation with the anatomical sex; hormones and neurochemicals, constantly changing the brain state, not taken into account. ‘Gender’ constitutes in this sense the key term that is being posed and reposed, thought and rethought, done and undone. My paper will be thus divided into three parts that shall refer to a critical vision of gender categories in various discursive domains. First part will treat the intrinsic introduction of gender as notion during the feminist movements of the 1960s and 1970s in an effort to contest the naturalisation of the bipartite sex difference of men from women, male from female, in multiple arenas of struggle. Despite having passed from the ‘biological’ (sexual difference) to the ‘ontological determinism’ (desire) through the ‘social constructivism’ (power), the notion of “gender” remains trapped within the oppressive Western binarism culture/nature, and therefore the second part will explore the new ways of thinking gender that emerge in the 1990s towards a deconstruction or denaturalisation of this notion; that is, gender as representation and as subjective identity. Although Butler’s theory of performativity did succeed not only to disqualify normative analytical categories leading to univocity, such as sex or nature, but also to release both genders and their social frame of reference from any determinism, the third part will not only show in what extent this very notion of gender (as doing) is nowadays again in crisis but also inquire the possible explanations for the impoverishment of gender and therefore for the necessity of its undoing. A mysterious elsewhere will emerge as a sort of agency that motivates us and establishes our sexuality, whose full meaning we ignore. The innate neurochemical biology of Brizendine will thus broaden up the cognitive fields and open new perspectives of rethinking gender, the mysterious elsewhere and -why not?- biology itself. "