The belief that we are all free agents - responsible for our actions and in a position to be punished for our crimes, seems to be a belief that most people subscribe to. But although such a belief may do wonders for our self-esteem and sense of human dignity, is there any evidence that it is true? In the face of immense problems - pollution, overpopulation, famine and possible global war - we urgently need a scientific understanding of how we are moulded by our environment. By losing our arrogance, argues the author, we can learn to control our destiny.