Why isn’t Caster Semenya at the World Athletics Championships?

South African runner Caster Semenya won’t be at the World Athletics Championships in Budapest, Hungary. It’s because she has differences of sexual development - or DSD - and isn’t allowed to compete in any track events without taking testosterone-reducing drugs.

But what is DSD? And why is it stopping Caster from competing? Celestine Karoney from BBC Sport Africa explains.

Plus, we’re joined by Frances Mao who talks us through recent 'Mudjima' knife crimes in South Korea.

Email: whatintheworld@bbc.co.uk WhatsApp: +44 0330 12 33 22 6

Presenter: Hannah Gelbart Producers: Emily Horler, Mora Morrison and Julia Ross-Roy Editors: Verity Wilde and Simon Peeks