In No Two Alike, Judith Rich Harris presents a fascinating exploration of human nature that looks within the mind to discover why people differ in personality. The detective work Harris began in her controversial book The Nurture Assumption has its triumphant conclusion in No Two Alike. Harris tackles a question that has long been a mystery: why do identical twins who grow up together - with the same genes, reared by the same parents - differ in personality? Her ground-breaking answer - the first completely new theory of personality since Freud - is based on principles of evolutionary psychology, bolstered by evidence from a variety of sources including studies of language, memory, autistic children, chimpanzees and even ants. This is the story of a scientific quest but it is also the personal story of a startlingly innovative woman who dared to question the accepted gospel in her field of expertise.