A pretty good article on why the claims of the IBA (in the boxing situation) about "failed" gender/sex tests are being met with skepticism:
Banned governing body that's fueling outcry on Olympic boxers has Russian ties and troubled history
The allegations that Olympic boxers Imane Khelif and Lin Yu-ting failed an eligibility test for women's competition have been made by only the International Boxing Association
abcnews.go.com