Who Do You Think You Are? is a British genealogy documentary series that has aired on the BBC since 2004, in which celebrity participants trace their family history. It is made by the production company Wall to Wall. The programme has regularly attracted an audience of more than 6 million viewers. More than ten international adaptations of the programme have been produced. (source Wikipedia)
The celebrities of this Who Do You Think You Are? episode are Alexander and Chris van Tulleken. Alexander “Xand” van Hoogenhouck-Tulleken and Christoffer “Chris” van Hoogenhouck-Tulleken, known as “Dr. Chris” and “Dr. Xand” are British doctors, television presenters and identical twin brothers. (source Wikipedia)