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