In a move that has sparked a debate among sportspersons and scientists globally, the International Olympic Committee (IOC) has affirmed that only “biological females” would be eligible to compete in any women’s sports at the Olympic Games or other events under its purview. On March 26, the Switzerland-based organisation announced female athletes at such competitions will have to undergo mandatory screening for the sex-determining region Y (SRY) gene. Any athlete who tests positive for the gene, commonly known as a marker responsible for triggering male biological development, will be barred from the women’s category.
IOC has framed this decision as a scientific intervention to provide “fairness, safety and integrity” to female competitors. It has stated that the screening will comprise a simple cheek swab or blood test; will be done only once during an athlete’s career unless there is reason to doubt the result; and will not be retroactively applied.
Since then, sportspersons, gender-rights activists as well as scientists have criticised the policy.
Typically located on the Y chromosome, SRY is often described as the “master switch” or “starting gun” for male development. According to geneticist Andrew Sinclair, who led a UK-based research team that discovered the gene in 1990, SRY becomes active around the six-week mark in a developing embryo. It triggers a cascade of events in 30 other genes, leading to formation of testes.
But a starting gun does not guarantee a race will be run. Individuals with SRY genes can be born as females. “Biological sex is much more complex, with chromosomal, gonadal (testis/ovary), hormonal and secondary sex characteristics all playing a role. Using SRY to establish biological sex is wrong …
This article was originally published in the May 1-15, 2026 print edition of Down To Earth