This week is all about twins. On today's programme we'll hear from a very special pair who are through to the final of the All in the Mind Awards, which celebrates those who have made a real difference to people’s mental health. We'll hear how the special bond between Lisa and Rose Betts really mattered when Lisa was going through a very tough time with her mental health.And the insight Lisa and Rose give us into their world got us thinking about the unique science of twins. What is it that fascinates us so much - and what can twins teach us about ourselves and the human experience?Claudia is joined in the studio by Daryl O’Connor, professor of psychology at the University of Leeds, and handily a twin himself, to dive headfirst into the evidence on twin relationships.Presenter: Claudia Hammond Producers: Gerry Holt (a twin) & Hannah Fisher Studio Manager: Tim Heffer Editor: Glyn Tansley Production coordinator: Jana Bennett-Holesworth (has twins)If you are suffering distress or despair, details of help and support are available at BBC Action Line.