It’s 1973 and the UK is in crisis: runaway inflation, industrial strike action and political turmoil. Unnoticed at the time - in hospitals and front rooms around the country - something odd is happening with the country’s newborns. A higher proportion of boys are being born than ever before in the 20th Century. What was behind this puzzling trend?

Hannah Fry follows one researcher’s obsessive mission to unravel the mystery.

Episode Producer: Ilan Goodman

A series for Radio 4 by BBC Science in Cardiff.