This is an extension of Gadpaille's major work in elucidating the formation of healthy psychosexual identity in children and adolescents. He concludes, through much cross-cultural research (with reference to nonhuman mammalian studies as well), that the various stages of sexual identity (i.e., gender identity, sex-role consolidation, sexual choice, comfort with genital sexuality) have relatively fixed, innate critical periods for development. Adolescents in our society have much discomfort with, fear of, and guilt about their sexuality. This constitutes a lack of "heterosexual readiness," caused by enormous prohibition during the critical period of children's curiosity and exploration of their own bodies and those of children of the opposite sex. There is "a remarkable infrequency of either sexual deviations or sexual dysfunctions in cultures permissive of childhood sex play and curiosity."