The diverse historical, cultural, and physiological influences that determine sexual orientation are the focus of this fascinating work by one of the foremost investigators of human sexuality. Drawing on case studies from his sexology clinic, the author explores such topics as prenatal and postnatal history, gender differentiation in childhood, and postpubertal hormonal theories. In so doing, he addresses the many enigmas of sexual orientation: What makes some children grow up to be homosexual, while others become heterosexual or bisexual? To what degree is gender identity determined before birth? How do the concepts of masculine and feminine become differentiated during childhood? What do we know about the relationship between hormones and homosexuality in adulthood? A unique feature of this book is the follow-up reporting on Money's long-term studies that began over three decades ago. The studies are brought together here for comparison with one another--and with the work of others--and their full significance is systematically evaluated. Also explored here is his pioneering concepts of lovemaps, the pathways of individual sexual and erotic development, and the factors that may shape overall healthy or pathological orientation, paraphilia, and gender transposition in childhood, adolescence, and maturity. Written in accessible language for researchers and clinicians, this authoritative work is both thought-provoking and informative as it explores timely questions of sexual orientation.