Chris van Tulleken is determined to improve his relationship with his twin brother Xand and, in the process, understand what change is and whether any of us can change who we are. Show more

Chris and Xand take a personality test to find out whether birth order has any effect on our personality. They encourage their immediate and extended family to do the same. Show more

Psychologist Wendy Johnson drills into the contentious debate around nature and nurture and Chris considers how much power he has to change his and Xand’s relationship. Show more

Chris wonders how easily we can harness willpower to make changes in our lives or if it’s an elusive concept. Xand can’t find the willpower to get on his exercise bike. Show more

Chris confronts the changes he needs to make to improve his relationship with Xand, like being a better listener. Xand wants Chris to join him in his pottery shed. Show more

Chris and Xand van Tulleken at the Hay Festival, reflecting on lessons learnt about their health and relationship while recording their podcast, A Thorough Examination. Show more

Prof Sarah Garfinkel tests the twins’ ability to interpret their inner emotions with surprising results. Is this why changing and improving their relationship is proving difficult? Show more

The twins meet a social worker helping families to make positive and sometimes urgent changes in their lives. Show more

Drs Chris and Xand van Tulleken explore if people can change and how they do it. How much of our personality is genetic destiny and how much are we shaped by the world around us? Show more

The van Tulleken twins consider how easy it is to roll out change on a large scale and ask Will Norman how he manages to implement change in the face of opposition. Show more