Is sex still binary?

Abstract

In this perspective article we discuss the limitations of sex as a binary concept and how it is challenged by medical developments and a better understanding of gender diversity. Recent data indicate that sex is not a simple binary classification based solely on genitalia at birth or reproductive capacity but encompasses various biological characteristics such as chromosomes, hormones, and secondary sexual characteristics. The existence of individuals with differences in sex development (DSD) who do not fit typical male or female categories further demonstrates the complexity of sex. We argue that the belief that sex is strictly binary based on gametes is insufficient, as there are multiple levels of sex beyond reproductivity. We also explore the role of sex in sex determination, gene expression, brain development, and behavioural patterns and emphasize the importance of recognizing sex diversity in personalized medicine, as sex can influence disease presentation, drug response, and treatment effectiveness. Finally, we call for an inter- and transdisciplinary approach to study sex diversity and develop new categories and methodologies that go beyond a binary model.

Figure 1:

The sex spectrum (modified from Ainsworth, 2015)

Figure 2:

Multiple logics of seeing sex/gender diversity and (non-)binarity: a) as a spectrum with overlaps, which may constitute DSD, b) reduction to a binary on a deeper ontological level, c) with a “third option” in between, in German law called “diverse”, d) non-binary people as both sexes, or “two spirits”, e) as a continuum with multiple options to distinguish between sex/gender categories, depending on contexts.