This book challenges the basis of Freudian psychology by showing that its explanation of the incest taboo is unfounded. In 1891, Westermarck proposed that early childhood association inhibits sexual attraction, an aversion manifest as the incest taboo. His argument was widely accepted until 1910, when Freud argued that young people's early sexual feelings are 'invariably' incestuous. The incest taboo existed, to thwart this natural propensity. Besides data on 14,200 Chinese women, many reared with their husband from early childhood, the book uses a wide range of research - from African divorce to animal behavior - to prove that Freud was wrong. It shows that there is a critical period in childhood during which association permanently inhibits sexual attraction. The incest taboo is thus unnecessary, and early association between father and daughter is the best preventer of sexual abuse.