This year’s Paris Olympics was not without controversy - most infamously for the gender row in boxing. Algerian Imane Khelif and Taiwanese Lin Yu-Ting were questioned for their participation in women’s boxing despite them being disqualified in last year’s world championships for failing to meet the eligibility criteria. But nothing is black and white, to dive into differences in sex development and how (or when) it matters in sports, we have our guest Dr Alun Williams, professor of sport and exercise genomics from the Manchester Metropolitan University Institute of Sport.