Series exploring topical scientific issues. Michael Mosley explores the latest theories on how our personalities are created - and whether they can be changed.

Michael Mosley explores the latest science about how our personalities are created - and whether they can be changed.

Despite appearances, Mosley is a pessimist who constantly frets about the future. He wants to worry less and become more of an optimist.

He tries out two techniques to change this aspect of his personality - with surprising results.

And he travels to the frontiers of genetics and neuroscience to find out about the forces that shape all our personalities.