What can doppelgangers tell us about nature v nurture?

The thing about doppelgangers is that despite looking almost identical, they aren’t biologically related. So, what makes them appear so similar? How do totally different people end up with the same face? And, can studying doppelgangers tell us anything about the age-old question of nature v nurture? Madeleine Finlay speaks to Dr Manel Esteller to find out. Help support our independent journalism at theguardian.com/sciencepod