Sexual behavior is not only of basic biological importance, but of central social importance. Not only does it perpetuate the human species, but it is the central behavior around which families are formed and defined, a vital aspect of the psychological wellbeing of individuals, and a component of a variety of social problems. Among current concerns tied in part to sexual behavior are the familial problems of marital harmony and divorce; criminal problems of rape, incest, child molestation, and prostitution; reproductive problems of infertility, sterility, unwanted and mistimed pregnancies, and abortion; and health problems related to sexually transmitted diseases (STDs).