sexology -
The study of sex and sexuality, usually from a psychological or clinical perspective.
Wikipedia
Sexology is the scientific study of sexual interests, behavior, and function. It is specifically a field of the research-based sciences; as such, sexology is distinct from the more general study of sexuality which may or may not incorporate explicitly scientific research methods. In modern sexology, researchers apply tools from several academic fields, including biology, medicine, psychology, statistics, epidemiology, sociology, anthropology, and criminology.
