Testosterone Concentrations and 2D:4D Digit Ratio in Heterosexual and Masculine and Feminine Lesbian Women

Objective Intrauterine exposure to testosterone (T-intrauterine) can permanently organize the brain. A putative marker of this endocrine exposure is the 2D:4D finger-digit ratio. In contrast to early prenatal androgen, testosterone concentrations in adulthood (T-adult) are purported to have transient activational effects. Lesbian women typically show lower 2D:4D ratios (indicative of greater T-intrauterine) and higher T-adult levels compared to heterosexual women. However, few studies, with mixed results, have assessed differences in T-adult and T-intrauterine between heterosexual, femme, and butch lesbians (respectively, feminized and masculinized styles). This study aimed to compare the 2D:4D ratio and T-adult levels in saliva between masculine, feminine lesbian, and heterosexual women. Results T-adult levels were higher in masculine compared to feminine lesbians and heterosexual women. However, there were no differences between the groups regarding the 2D:4D ratio, nor did it show a correlation between T-adult levels and the 2D:4D ratio. Conclusion Our study suggests the existence of biological differences at the activational level between masculine and feminine lesbians. These results do not exclude the possibility of prenatal influence on female homosexuality. We recommend further studies to address this question while circumventing the limitations of the present study.