The sexual adjustment and behavior patterns, often referred to as sexual personality, of human beings are probably more varied and divergent than almost any other aspect of their diversity. Scientific interest has hitherto centered either on abnormalities, which have been exhaustively studied in the form of case histories and anecdotes by psychiatrists and psychoanalysts, or a census-type data collected on large samples, "broken down," as the saying goes, by age and sex—Kinsey's work is an example of this type of approach. We learn from published data that Americans on the average have intercourse two to three times a week, but this kind of information is almost useless when it is realized that some people have intercourse once a month, while others have intercourse several times a night—the wife of the "Boston strangler" complained that her husband insisted on having intercourse something like 14 times a day! ("Complained" is the operative word—some women might have welcomed such dutiful attendance.)
Sigmund Freud was a famous neurologist, popularly known as the father of psychology. Thanks to his teachings in the late 1850s, people have spent thousands of dollars to sit on a couch and tell a complete stranger how they really feel about their mother – and why it strangely turns them on.