Younge correctly notes that identity is dependent not only on the individual but also the behaviour of the wider world. There are fascinating tales, such as the black girl born to white South African parents and the son of a Jewish leader who was judged not to be Jewish. In the book he weaves his own story – the working-class son of a single mother from Barbados, who was raised in Stevenage and now lives in the United States – with powerful reportage from across the globe that reveals the changing nature of identity. There are few journalists better equipped to navigate this territory than Younge, not only because of his experience as a foreign correspondent for this newspaper but because his own biography demonstrates the fluid nature of identity. 'Because their identity is never interrogated they are easily seduced by the idea that they do not have one.' Among the great merits of Younge's book is that he reminds us – and them – of the falseness of that assertion. 'The more power an identity carries, the less likely its carrier is to be aware of it as an identity at all,' Younge notes. It was only after reading Who Are We?, Gary Younge's penetrating and provocative new book, that I realised the best response to her question would have been to turn the tables on my interrogator and demand to know where she was from. Since she appeared not to be persuaded by my honest answer that I was British I eventually explained that my family were originally from Pakistan, and this satisfied her.

Neither my passport nor my accent nor the fact that I had spent virtually my entire life in Britain qualified me, in this woman's eyes, as British. 'Well, you speak with a British accent,' she said, 'but you're not white like me, so where are you from?' For non-white travellers, such incidents are familiar and a reminder that identities are not wholly ours to define.

'Oh, can't you tell?' I said, smiling and taking care to over-articulate my words. 'Tell me, where are you from?' she asked, after we had been chatting for a few minutes. On a recent visit to Amsterdam I fell into conversation with a woman who owned a gift shop.

Who are we