As globalisation continues a pace, violent conflict forces millions to seek a home elsewhere, and the internet makes it easier for us to choose what news we consume, people around the world are starting to question their sense of identity. What defines us? Is it our nationality, our region, our religion, age or habits? Is it our political preferences, or the football team we support? And is there any room left for nation states, when so many of the big decisions facing the world are now taken at a supranational level?