In his introduction, he states that he wrote this book to summarize the findings of his work on the sexology of sexual orientation, or "what determines that some children grow up to become homosexual, whereas others become bisexual or heterosexual." Additionally, he presents strong opinions on, among other things, cultural attitudes toward sex, pornography, and the treatment of sex offenders. His writing sometimes has an edge that apparently arises from the author's political battles (referred to in the introduction) and from the vehemence of his beliefs. However, he scatters a great deal of information through the book, addresses a number of controversial issues, and makes some interesting points.The book is divided into four chapters: "Prenatal Hormones and Brain Dimorphism," "Gender Coding," "Gender Cross-coding," and "Lovemaps and Paraphilias," as well as