Davina McCall and Nicky Campbell present a special edition dedicated to the stories of twins separated at birth. Mary Holmes and Elaine Allin were born just after the Second World War and raised in the same neighbourhood in Chesterfield, but forbidden from seeing each other. It wasn't until they were in their thirties that the sisters were able to find each other - and even then it only happened by chance. There is also a look at the latest scientific research into what it is really like to be separated from a twin at a young age.