Non-medical sex selection is premised on the notion that the sexes are not interchangeable. Studies of individuals who undergo sex selection for non-medical reasons, or who have a preference for a son or daughter, show that they assume their child will conform to the stereotypical roles and norms associated with their sex. However, the evidence currently available has not succeeded in showing that the gender traits and inclinations sought are caused by a “male brain” or a “female brain”. Therefore, as far as we know, there is no biological reason why parents cannot have the kind of parenting experience they seek with a child of any sex. Yet gender essentialism, a set of unfounded assumptions about the sexes which pervade society and underpin sexism, prevents parents from realising this freedom. In other words, unfounded assumptions about gender constrain not only a child’s autonomy, but also the parent’s. To date, reproductive autonomy in relation to sex selection has predominantly been regarded merely as the freedom to choose the sex of one’s child. This paper points to at least two interpretations of reproductive autonomy and argues that sex selection, by being premised on gender essentialism and/or the social pressure on parents to ensure their children conform to gender norms, undermines reproductive autonomy on both accounts.