Many of us are fascinated by our ancestry: knowing where our families came from can give us a sense of identity and roots. Tracing your family tree is a time-honoured tradition, but several companies now sell DNA tests that offer you insights into your heritage: so you might find out you’re 70% Nigerian, 39% Italian, or 11% South Asian, for example.

There’s no doubt that genes contain clues about your family history, but how reliable are these commercial tests? That’s what CrowdScience listener Karen wondered after an update of her test results showed her going from 39% Scandinavian to 2% Norwegian. How confident can she be in her results now? And what does it actually mean to be 2% Norwegian, in terms of your family tree?

Presenter Alex Lathbridge delves into his own African and European ancestry, talks to some of the companies offering these tests, and unpicks the complex relationship between genetic science and family trees. We meet a woman who found her long-lost uncle with a combination of a DNA test and old-fashioned archive research; and look to the Americas to ask whether genetic testing can restore ancestral ties erased by the inhumanity of the transatlantic slave trade.

Presented by Alex Lathbridge

Produced by Cathy Edwards for the BBC World Service

(Photo: Elderly hands looking at old photos of self and family. Credit: Getty Images)