In this brochure, the famous St. Petersburg sexologist and psychotherapist, candidate of medical sciences Dmitry Isaev, in a clear, accessible language, talks about the various stages of the formation of human sexuality from infancy, preschool, school and adolescence up to adulthood. Based on the richest, well-illustrated material and Using the latest medical research data, the author unfolds a panorama of human sexual development that will interest people of all ages - high school students, their parents, as well as all those who are interested in aspects of the sexual development of a person as an individual.