evidence: "This is what is called the make-male gene. It’s the master switch of sex development," says Dr Emma Hilton, a developmental biologist who studies genetic disorders. She is also a trustee of the Sex Matters charity, which argues Imane Khelif and Lin Yu-ting shouldn’t be competing until further testing is done. [...] So a test that identifies XY chromosomes does not offer a complete picture. And in the case of Imane Khelif and Lin Yu-ting, the IBA has not disclosed details of the way they were tested. [...] When it comes to Imane Khelif and Lin Yu-ting, we don’t have enough information to know if they have a DSD that would need to be regulated.