March 26, 2026

expert reaction to the International Olympic Committee (IOC) announcing new Policy on the Protection of the Female (Women’s) Category in Olympic Sport

Scientists comment on the International Olympic Committee (IOC) announcing a new policy on the female category in Olympic sport. 

Prof Alun Williams, Professor of Sport and Exercise Genomics, Manchester Metropolitan University, said:

“There’s appropriate concern about fairness and safety in women’s sport, but genetic testing of all competitors isn’t the right approach.

“If the concern is about transgender women athletes, genetic tests aren’t needed. A combination of paperwork including sex registered at birth, testimony from those who knew those athletes when they were younger, and asking the athletes themselves, would identify those athletes accurately. This means the genetic testing in the IOC policy is mainly to identify athletes recorded female at birth, who have lived their whole lives as girls and then women and who have a rare genetic characteristic that affects the development of their reproductive and hormonal systems. This is usually called a Difference of Sex Development (DSD).

“There’s no convincing direct evidence that athletes with DSDs have advantages in sport. What little evidence there is extremely low quality – some of that is addressed in our recent editorial in the British Journal of Sports Medicine authored by 34 scientists, clinicians and ethicists ^[1].  Therefore, excluding athletes with DSDs from women’s sport is based on inference rather than direct evidence – inference that because in some cases they have circulating testosterone in the typical male range, they must have the same advantage that all men do. But their rare genetic characteristics mean that (depending on the category of DSD) they cannot either sense or process testosterone in a normal way.

“Genetic testing of all girls and women athletes comes with huge financial, practical and ethical problems. For example, athletes are coerced into taking the genetic test because the only other option is to stop competing forever. Also, for any genetic test with the potential to reveal life-changing information that can be devastating for an athlete and their family, genetic counselling should be provided to every individual before the genetic test is done, and that isn’t part of the IOC policy.  The financial cost and availability of appropriately trained counsellors are prohibitive, but that doesn’t mean the need for proper genetic counselling can just be ignored. IOC events include the Olympic Games and the Youth Olympic Games for 15-18 year olds, and the new policy applies to all IOC events, so it applies to teenage girls long before any of them become professional athletes. However, if genetic tests are conducted at 15, a promising young athlete with a DSD who ‘fails’ the test will not be able to retain their privacy – it will be evident to coaches, friends, and competitors why they no longer compete. Privacy could be somewhat better maintained if genetic tests were conducted much younger than 15, i.e., before a girl athlete is known to many people in their sport, but that would amplify the ethical concerns of testing young athletes’ DNA without proper understanding and consent, and mean many more young girl athletes would need to be tested just in case some of them became good athletes in the future.

“I acknowledge that some scientists and clinicians involved with sport hold different views and believe that the new IOC policy is the right one. However, few of them acknowledge the problems it generates – in my opinion, their argument would be more coherent if they acknowledged the problems and argued they were justified and a necessary evil, instead of pretending the problems don’t exist.

“What’s certainly true is that genetic testing like this was tried and then abandoned in the 1990s because of all the inherent problems with validity, practicality and ethics. Whatever the reason, that abandoned approach is now making a return, but it still suffers from all the same problems as before.”

References:

[1] https://bjsm.bmj.com/content/60/7/497

Prof Ashley Grossman FMedSci, Emeritus Professor of Endocrinology, University of Oxford, said:

“I am not an expert on DSD athletes in sport, but for transgender females, the evidence is clear that proceeding through male puberty, regardless as to whether testosterone is subsequently suppressed to ‘female’ levels in adult life, provides a clear advantage in many physical and contact sports. I would quote the papers ^[1,2] we (as Editor-in-Chief) published a year or two back, and then discussed with few negative comments at the US Endocrine Society last summer in San Francisco.

“I would emphasise that it is not directly relevant to DSD, but I am happy that they have decided that Complete Androgen Insensitivity Syndrome (CAIS) athletes can be considered female regardless of their XY karyotype because their Y chromosome leads to testosterone production but this is inactive, so they have not experienced male-related testosterone effects at any point in their lives.”

References:

[1] https://www.sciencedirect.com/science/article/pii/S1521690X25000387?via%3Dihub

[2] https://academic.oup.com/edrv/article/45/5/709/7641481

Declared interests

Prof Ashley Grossman: “I have no COI.”

For all other experts, no reply to our request for DOIs was received.