Surely one of the most controversial areas of human behavior is that of sexuality and sexual orientation. Both psychology and behavioral genetics are now wracked with divisive arguments about the origins of sexual orientation. In fact, psychologists have been arguing about what causes homosexuality for more than 100 years, and they are actually further from consensus now than they were a decade or two ago. Psychological explanations of homosexuality, based on the teachings of Freud, were widely accepted until fairly recently. But Freudian explanations have wilted in the face of conflicting data, and most psychologists have concluded that a new theory of sexual orientation is needed. Similarly, behavioral geneticists are deeply divided about the validity and significance of several recent high-profile studies on the inheritance of sexual orientation.
Freud believed that every child is inherently bisexual at birth, but during a particular stage of development that occurs at about 4 years of age, this changes. Children learn to suppress sexual feelings toward members of the same sex, and to direct sexual feelings toward members of the opposite sex. Freud proposed that male homosexuality originates when this developmental stage is blocked, perhaps because of the presence of a domineering mother figure or the absence of a strong father figure. This "psychodynamic theory" of homosexuality predicts that homosexual men would tend to be emotionally distant from their father and perhaps emotionally dependent on their mother. However, when this prediction is actually tested, it is usually found to be quite weak.