"The IOC states that SRY gene is a reliable test for determining biological sex and therefore who can complete in women’s events.

However, this policy is based on the overly simplistic idea that the presence of the SRY gene alone is equivalent to being male.

Male sex is much more complex, involving multiple genes other than SRY in developmental pathways as well as hormones. The presence or absence of the SRY gene does not determine the range of human sex characteristics. Individuals with differences of sex development may carry the SRY gene but develop either complete or partial female bodies while others develop male bodies but lack SRY.

All the SRY test tells you is whether or not the gene is present. It does not tell you how SRY is functioning, whether a testis has formed, whether testosterone is produced and, if so, whether it can be used by the body.

The SRY gene alone should not determine who can compete in women’s sport."

Andrew wrote a Conversation article on World Athletics'  mandatory genetic tests. See the article here.

"This policy represents a significant and concerning shift in how international sport approaches gender eligibility. It moves the Olympic movement away from inclusion and toward a blanket, exclusionary rule that disproportionately targets a very small and already marginalised group of athletes. From both a human rights and a sporting perspective, this is not a positive development. It risks undermining the Olympic values of inclusion, respect, and fairness - not strengthening them.

While fairness in women’s sport is often positioned as the central concern, we need to be clear that the science in this area is not settled in the way it is often presented. Claims about fairness are often framed as if they are settled science, but this simply isn’t the case. The current evidence base is limited and mixed, and does not demonstrate that transgender women retain a systematic or universal advantage following gender-affirming hormone therapy. One thing we do know, however, is that human bodies vary enormously, and that variation cannot be reduced to a simple male-female binary. As such, policies that impose blanket exclusion go beyond what the science can reasonably support. There is also a real risk that increased scrutiny of eligibility will spill over into broader policing of women’s bodies, particularly for those who do not conform to narrow expectations of sex and gender.

• Decisions like this send broader social messages about who belongs in sport. The number of transgender athletes at this level is extremely small, but the symbolic and cultural impact of exclusionary policies like this is much wider.
• Human bodies are more diverse than a simple male–female binary - sport policy needs to catch up with that reality.
• Policies like this don’t just affect trans athletes - they reshape how all women’s bodies are scrutinised."

"The Human Genetics Society of Australasia (HGSA) is the peak body representing the human genetics workforce in Australia and New Zealand.

The HGSA does not support the use of mandatory genetic testing in any setting, nor the use of genetic testing for non-clinical or discriminatory purposes. We are concerned about the IOC policy, the associated precedence of using genetic testing for mandatory, non-medical purposes, and the appropriateness of the proposed testing procedure.

Core principles of genetic testing include voluntary consent, provided free of coercion, with access to appropriate support services, and performed for the health benefit of the individual. Genetic testing performed outside of these guardrails has increased potential for harm, and risks undermining public trust for genetic tests, which if used appropriately, have enormous and proven benefit to the health and wellbeing of those who need them.

We do however appreciate that athletes who will be affected by this policy have trained hard for many years to achieve their goals, and will have no choice but to take the test to continue to compete. Where testing is performed, it has to be under a harm minimisation approach that ensures athletes have access to appropriate information and support services to make informed decisions about the potential implications of testing."

"The presence of the SRY gene does not define sex in all cases.

This is a complex area and there is no single test that can fairly and definitively prove a person’s sex.

For example, I have been studying XY females with the SRY gene - a condition known as Swyer syndrome - for 20 years.

XY females might have a change in the SRY gene, but most do not. It could be in any of dozens of other genes - or not even be known.

The transgender woman athlete may carry the SRY gene, there is little scientific evidence that the gene delivers any physical benefits in sport."

"This is not only a story about elite sport, but has a knock-on impact on children in community sport. Playing sport gives us a community where we belong, a place to have fun, and is great for our physical and mental health. Trans children and young people drop out of sporting activities at earlier ages than their cisgender peers. These children face barriers to playing in community sports teams, such as rules around uniforms, gender segregation and administrative requirements around documentation.

Exclusionary rules at elite levels, and the subsequent escalated controversy, impact on children being able to play local sport in kind communities where they can feel they belong. The exclusionary rules give other sporting bodies and communities permission to exclude trans children from sport, reducing kindness in local communities. Sport gives trans kids a place to be affirmed in their gender, which is crucial for their wellbeing.

My research with parents shows the work that parents do to support their trans children to play, because they see the positive impact of this participation (see new article)."

"It’s clear that the IOC had to do something to address the issue of fairness in sex-based competition. The proposed test for SRY is a good place to start: it is scientifically based, non-invasive, simple to perform, and discreet. While some will contend that the test’s accuracy is not 100%, this may be a case of the IOC having to not let the perfect be the enemy of the good. Based on available scientific evidence, the mere presence of SRY will be sufficiently accurate to determine biological maleness in well over 99% of cases."

"This debate appears to be conflating two different groups of people: trans athletes and athletes with differences of sex development.

This test is not a good way of determining biological sex, so it will not solve any perceived problem of fairness, and it may well cause a great deal of harm to individuals with differences of sex development, who were not previously aware of this.

Genetic testing of this kind requires appropriate genetic counselling, including a thorough discussion of the risks and possible outcomes, for consent to be in any way valid. This is not a test being done for clinical purposes, but for misguided social reasons, and in a way that misunderstands the science. The athletes will feel they have no choice but to take the test, which violates fundamental principles of medical ethics. The lack of safeguards – such as standardised genetic counselling protocols, privacy protections, and equitable access to testing – further amplifies these harms, particularly in low-resource settings.

Mandatory testing in contexts where valid consent cannot reasonably be obtained is only justifiable in strictly limited circumstances, and usually where harm to others (e.g. breath testing for alcohol in drivers) or individuals (e.g. anti-doping testing in sport) is a legitimate risk. As SRY gene testing neither protects against harm nor ensures fairness in sport, it is not justifiable to impose upon athletes unable to consent freely to testing."

"The IOC's decision is a clear setback for women's sports, as it will require all women athletes to submit deeply personal information at an increased cost. I expect the following outcomes:

1.) Due to human genetic diversity, some people who are cis women will be declared "men" by the IOC's testing. In addition to being excluded from their sport, this can have devastating psychological consequences. Gender and sex are not determined by a single gene. 
2.) More women will be excluded from sport due to being unwilling to undergo testing. This will be an invisible consequence, as these potential Olympians will not progress. 
3.) Women will face more barriers to play, as there is an increased financial cost to do so. 

Unfortunately, this decision is not grounded in sound science and targets a minority population – expressly transgender women – while costing all women more. We already have evidence that transgender women do not have a competitive advantage in sport, yet are often discriminated against, despite the UN declaring participation in sport a fundamental human right."

"I’m concerned that the IOC’s move to mandate sex testing across the female category risks undermining both evidence-based policy and athlete wellbeing, while diverting attention from the real priorities in women’s sport. The best available data, including a large systematic review of more than 6,000 participants across 52 studies, show that transgender women receiving gender-affirming hormone therapy are not meaningfully different from cisgender women in key performance-related measures such as muscle mass, strength, body composition, or cardiorespiratory fitness and in many aspects have a disadvantage. While some differences, such as height, may persist, these do not translate into a consistent competitive advantage. Importantly, the current evidence does not support the idea that prior male puberty confers a permanent, universal advantage once someone is on hormone therapy, and these policies also capture trans girls who have never experienced male puberty, for whom there is no physiological basis to suggest any advantage. 

There is also a long and painful history of sex verification in sport, where young women have had their dignity, privacy, and careers profoundly harmed through invasive and often arbitrary testing. Mandatory testing raises serious human rights, discrimination, and data protection concerns, and there is still no robust evidence that such policies are necessary or proportionate. In many ways, this represents a return to practices that were abandoned decades ago for good reason. If we are serious about fairness and advancing women’s sport, the focus should instead be on sustained investment in equitable funding and pay, safe sporting environments free from harassment, access to high-quality coaching and facilities, and greater visibility in media coverage. Fairness and inclusion can coexist, but they require nuanced, evidence-informed policies alongside meaningful structural support for women’s sport."

"There is really no 'level playing field'; elite athletes are off the scale in many genetic attributes. Hard to find a fair solution, given that transwomen who developed as males would certainly have physical advantages; for instance, a larger heart, faster muscles on average. We are beginning to understand just how different male and female development is - a third of our genes act differently in many tissues of males and females. The only fair alternative I can think of is to go for a grading system like the Paralympics."

"This decision is deeply troubling because it turns trans people into a target of exclusion and sits uneasily with core human rights principles of equality, dignity and non-discrimination.

Blanket exclusion and coercive testing of transgender athletes is a blunt and discriminatory response that is not supported by science and violates international human rights law. Mandatory genetic sex testing and rigid biological criteria as a condition for participation in the women’s category violates fundamental and universal human rights as set out in the International Covenant on Civil and Political Rights, including the right to equality, non-discrimination, dignity, privacy and bodily integrity.

As several UN Independent Experts have noted, binary definitions of sex reinforce harmful stereotypes and erode progress toward substantive gender equality. Any testing of athletes needs to be individualised and evidence-based, not arbitrary, and degrading.

The IOC's decision is not particularly surprising given that the next Olympics are in the US, where President Trump seems to be on a mission to eradicate trans people. His campaign against trans people includes requiring visa applicants to the US to disclose their sex assigned at birth, and if it differs from the gender marker on their passport or other official documents, they risk visa denials or allegations of fraud. This recent change to immigration laws makes it highly unlikely that any trans athletes will be travelling to the US for the 2028 Olympics, regardless of the IOC decision. The IOC should revisit its decision ahead of the 2032 Olympics in Brisbane."