Gender is shifting. But is gender disappearing? This is the story of where biology meets behaviour - how sex drives us, and informs so many of the key choices we make in life. In the last century it was argued that men are from Mars and women are from Venus - but things have moved on a long way since then. In this timely new approach to the debate, Tom Whipple travels far and wide - from a Home Counties swingers' party to a gay penguin sanctuary in Germany - and draws on the latest studies in behavioural science as well as fascinating explorations into anthropology to present a surprising tale of expectations and mismatches. If you are currently single, this book is about your place in the dating market - your successes, your failures and what they mean. If you are in a relationship, it is about why you chose the person you are with, why they chose you - and the circumstances in which either of you might put it all at risk and stray. In X and Why, Tom Whipple delves into the sexual subconscious to explain the inner workings of character and desire. It will change the way you see yourself and everyone around you. 'This witty, racily-written book will ruffle some feathers. Some feathers need to be ruffled. Whipple does it with panache and style.' Richard Dawkins 'The science of sexuality is almost too interesting to read and write about, inviting cheap jokes and heavy-handed politicising. But Tom Whipple hits the spot, and presents the latest thinking and research with depth, wit and balance.' STEVEN PINKER, Johnstone Professor of Psychology, Harvard University, and author of How the Mind Works and Enlightenment Now