Biology is considered fundamental and bedrock according to the reigning sexological model, both in terms of distal (prenatal and early life)
and proximal (at the time of the sexual event or experience) control over sexuality. Sociobiologists and others insist that genetics and prenatal endocrinology create brain structures which determine aspects of sexuality such as sexual orientation, monogamousness, and any and all differences between men and women (LeVay, 1993). In puberty, changing sex hormone levels are said to initiate and stimulate sexual interests and activities. In adulthood, hormones are said to be mandatory for any sexual desire or arousal, although the research is often inconsistent as to which hormones cause which effects at which points in time (Fausto-Sterling, 1992; Vines, 1994). Biological alterations related to menstrual cycling, pregnancy, aging, diseases, and medications are said to exert profound influences on sexuality through direct effects on physical function, response, and desire.
A pervasive influence of biology within the sexological model has to do with the definitions of sex as a specific activity, penile-vaginal intercourse, (as in a question which may appear in a survey, “How many times did you have sex in the last month?”). If sex is assumed to be the act of heterosexual reproduction, unless otherwise specified (as, e. g., oral sex), then an unfortunate universality derived from biology is ascendant. Don’t forget that it was the physical experience and bodily changes during some acts of sexual intercourse that was called "the human sexual response” by Masters and johnson (1966). This particular physical experience of desire, arousal, and orgasm, again assumed to be transcultural and transhistorical, became the essence of sexual normalcy in the American Psychiatric Association’s (АРА) (1994) official manual of mental disorders.
Actually, the preeminence of biology in the sexological model is demonstrated by the listing of sexual dysfunctions that first appeared in the 1980 edition of the Diagnostic and Statistical Manual of Mental Disorders (АРА, 1980), and has continued, with very minor modification, into the 1987 and 1994 editions (Tiefer, 1992). The dysfunctions all have to do with impairments in the performance of intercourse, and specify the necessity of physiological arousal (genital vasocongestion), orgasm (not too soon and not too delayed), sexual desire (no genital aversion), no genital pain, and no vaginal impediment to intercourse. One important consequence of the accentuation of genital function as the focal point of normal and disordered sexuality in the sexological model of sexuality is that the medicalization of sexuality has become a major industry and domain of basic research, with mixed benefits (Tiefer, 1987, 1995).
How is the commitment to this bodies-ftrst position communicated by sexology? A statement such as, “The activities and physiological responses of the body are the central element in sexuality, and are universally defined and experienced,” would not be found in a sexuality textbook. Rather, the primacy of biology guides the conceptualization of sexuality implicitly rather than explicitly. Initial chapters in sexuality textbooks typically describe the biological basis for sexuality—introducing the reader to endocrinology, neuroanatomy, and genital physiology at great length. Once this basis has been described, the text can go on to dozens of human sexual topics (e. g., attraction and flirting, sexuality according to different religions, sexual problems and treatments, sexual abuse and its consequences), which never again mention any biological variables. Yet the primacy of biology (basic and bedrock), the implication that universal biological standards set the parameters, has been established by the book’s order of contents. Biology is presented as determined by genetics, embryology, or developmental biology. Absent is a discussion of how biological reactions can be learned, or that they may be expressed or experienced differently in different cultures. The model of biology that prevails is of a preexisting, evolution — dictated imperative. In a sense, the sexological model of sexuality has promulgated that old cliche, “anatomy is destiny.”