Feminist and trans theory challenges "the" binary sex/gender system, but can create a new binary opposition of subversive transgender versus conservative transsexual. This paper aims to shift debate concerning bodies as authentic/real versus constructed/mutable, arguing that such debate establishes a false dichotomy that may be overcome by reappraising scientific understandings of sex/gender. Much recent biology and neurology stresses nonlinearity, contingency, self-organization, and open-endedness. Engaging with this research offers ways around apparently interminable theoretical impasses.