Published in Scientific Reports, this study employs the twin design to disentangle the contribution of genetic inheritance and intrauterine hormonal factors to transgender and gender diverse identities.
The twin design is one of the most powerful methods for estimating the heritability of a trait, by comparing the concordance between monozygotic twins (who share 100% of their genome) and dizygotic twins (who share approximately 50%). Applied to gender identity, it allows separating the weight of genes from that of shared environmental factors.
The authors analyzed a registry of twin pairs in which at least one member identified as transgender or gender diverse, examining both concordance and differences in prenatal hormonal exposure, assessed through proxy markers such as hyperpigmentation or the digit ratio.
The results provide evidence of a substantial heritable component in diverse gender identity, while also pointing to the possible contribution of intrauterine hormonal exposure. The study underscores the multifactorial nature of the trait and the absence of simple determinism.
These findings have implications for understanding gender identity as a complex trait with a partial biological basis, and reinforce the need to investigate the interaction between genes and the hormonal environment during prenatal development.
Bibliographic reference
Conabere W, et al. Using twin data to examine heritable and intrauterine hormonal influences on transgender and gender diverse identities. Sci Rep. 2025;15(1):21680.
DOI: https://doi.org/10.1038/s41598-025-06265-6
PMID: 40594415
Publication access: the original reference can be consulted in open access or through the indicated DOI.
