svzn

There are athletic sex differences even amongst prepubescent children, mostly caused by the testosterone surge in utero.

See https://womenssportspolicy.org/pre-puberty-male-female-child....

The test is used for initial screening only.

Presence of SRY in an athlete registered as female means further tests must be undertaken, with permission of the athlete, to determine eligibility.

Absence of SRY means the screening is passed and the athlete is eligible to compete.

They're not all taking banned substances. Case in point, Hergie Bacyadan and Elis Lundholm competed in the last Summer and Winter Olympics respectively.

That athlete was excluded from the women's competition on the basis of having male physiological advantage. Exactly what the Olympics are now doing.