The reconstruction of the body in trans and intersex conditions has both a well-established history in the last few decades and a worrying conceptual incoherence. Whilst many of those seeking to cement genital identity may understandably see it as an acceptable and welcome intervention, going under the knife raises all sorts of theoretical and bioethical questions not simply for immediate participants but for the wider socio-psychic understanding of gender. We shall address the troubling dimensions of body modification through the lens of feminist and postmodernist thought, which intrinsically seeks to engage equally with the instability of biological identity and of sociocultural construction. The chapter will outline a broadly Deleuzian approach that posits the body as a dynamic assemblage and draws on recent research into microchimerism that throws further doubt on the problematic of sexual difference.