Is gender really as straightforward as we would all like to think? What is it that makes anyone a man or woman? A female athlete is the subject of international controversy surrounding her right to compete as a woman; a pre-pubescent girl demands medical treatment to prevent the onset of female puberty; a school-age boy lives his life as a girl with his parent's support. Questions about gender and identity are confusing and often generate controversy. More and more, stories about children "identifying" as the opposite sex, and parents allowing them to live their lives as the alternate, or even undergo medical interventions to prevent development as one gender or the other, raise questions about ethics, values, and science. Beyond X and Y looks at the science of gender identity and offers the personal stories of some of those affected by these questions. Leading us on a journey from chromosomes through evolutionary psychology and what makes us who we are, Jane McCredie includes stories of people from all walks of life and explores the science that is helping us answer these questions. She shows that we are far from "opposite" sexes and challenges everything you thought you knew about men and women.