Since the beginning of time, we've seen 'thought' as the product of reason, the work of the mind. We've learnt to present our arguments in rational order, and we've thought of our opinions as the beautiful result of reason and evidence. But this is only part of the story. A fascinating new body of research shows that almost everything we think - those complex justifications for lower taxes or prison reform, those long-pondered and sincere beliefs in God or Nothing, even the food we like or turn away from in disgust - has its roots in a mind-boggling collection of hidden influences - from our geography to our genes. Packed with surprising case studies and counter-intuitive research, this urgent and entertaining book reveals where our opinions really come from and what they are for.