Basal testosterone was not correlated was gender-stereotyped attributes.

Nor did it mediate sex/gender differences in these traits.

This result was found for between and within-sex analyses.

Self-perceived masculinity and femininity were related to these traits beyond sex.

Findings refute the activational testosterone-masculinity hypothesis.

Sex/gender differences in personality associated with gender stereotyped behavior are widely studied in psychology yet remain a subject of ongoing debate. Exposure to testosterone during developmental periods is considered to be a primary mediator of many sex/gender differences in behavior. Extensions of this research has led to both lay beliefs and initial research about individual differences in basal testosterone in adulthood relating to “masculine” personality. In this study, we explored the relationships between testosterone, gender identity, and gender stereotyped personality attributes in a sample of over 400 university students (65 % female assigned at birth). Participants provided ratings of their self-perceived masculinity and femininity, resulting in a continuous measure of gender identity, and a set of agentic and communal personality attributes. A saliva sample was also provided for assay of basal testosterone. Results showed no compelling evidence that basal testosterone correlates with gender-stereotyped personality attributes or explains the relationship between sex/gender identity and these attributes, across, within, or covarying out sex assigned at birth. Contributing to a more gender diverse approach to assessing sex/gender relationships with personality and testosterone, our continuous measure of self-perceived masculinity and femininity predicted additional variance in personality beyond binary sex and showed some preliminary but weak relationships with testosterone. Results from this study cast doubt on the activational testosterone-masculinity hypothesis for explaining sex differences in gender stereotyped traits and within-sex/gender variation in attributes associated with agency and communality.

Testosterone

Sex differences

Gender identity

Masculinity

Femininity

Personality

Agency

Communality

The data and R code for this study are available at the Open Science Framework repository: https://osf.io/bny4j/.

© 2024 The Authors. Published by Elsevier Inc.