Biology determines that people with XY chromosomes usually follow a developmental pathway in which testosterone, most notably,  impacts the muscle mass, bone development  and lung capacity that are relevant for speed, power and endurance. While it is clearly unfair that individuals with such sporting advantages  should compete against individuals without such a developmental pathway (‘males’ vs ‘females’), this does not always equate to an absolute definition of sex or gender. To try to tackle this issue, some federations are proposing to use the presence or absence of the SRY gene as a test in order to determine eligibility for the male or female sporting category. While it is the case that people with a positive SRY test usually have a more male phenotype, there should be room to consider exemptions both for XY people with a more female phenotype, and XX people with a more male phenotype. The SRY test would be used as a screening test to detect sporting advantages that would arise from sex-based androgenisation during development, for example through puberty, and therefore should be seen as a proxy and not considered to be definitive. Importantly, such determination is specifically meant to allow for eligibility in the female sporting category, and does not imply any assessment of a person’s experienced or legal identity.

The result of such a test cannot determine completely whether an individual should compete in the female category. Fine-tuning of protocols and exceptions will take time and careful consideration. It will also be very important that athletes receive medical and psychosocial support in the case of an unexpected test result. This should receive more prominent attention in protocols, and applies particularly to athletes who have previously competed in the female category and who may be totally unaware that they carry the SRY gene. The quality of the tests offered in different countries will also need proper control.

ESHG believes that it will be important for human geneticists to be involved in any working groups set up to discuss these issues, to improve societal discussions through increasing the understanding of the complexity of these matters, and to reduce the potential harms arising from the introduction of genetic testing for non-medical applications.