Psychosomatic Medicine 11:133-139 (1949)
© 1949 American Psychosomatic Society

Role of the Hormones in Human Sexuality

¹ Endocrine Clinic of the Philadelphia General Hospital

A reasonable approach to the problem of human sexuality must include careful analysis of the total individual. All three factors, which may influence the determination of sexual behavior, must be considered. The first is the genetic factor which predetermines the particular type of sexual pattern and which is constant within limits for any one species. This pattern will depend upon the anatomic configuration of the sexual organs and upon the neuromuscular and nervous pathways through which impulses must pass to result in effective utilization of these organs.

The second factor is hormonal. The androgenic and estrogenic hormones cause growth and development of the organs needed for the sex act. Androgens, furthermore, increase the sensitivity of these organs to mechanical stimulation so that the sexual pattern which has been determined genetically is more easily elicited. The gonadal hormones potentiate the inherent genetic sexual pattern. Other endocrine factors, such as the thyroid hormone, influence sexual behavior only secondarily because of their general effect on health and strength.

The third important factor is psychologic or learned. This, in the human, is a sufficiently potent mechanism so that sexual activity may be greatly repressed or increased, regardless of the endocrine status. It has been seen that genetic factors exert no influence upon the choice of the sex object. Hormones, likewise, do not influence the choice of the object of affection. The society in which we live teaches heterosexual love and the choice of the sex object is determined by learned experiences. In the usual course of events, the sex object is of the opposite sex. When psychosexual maturity has not occurred, homosexuality may result.

Beginning with the basic genetic pattern with which the infant is born, hormonal and psychologic influences are gradually added. Early in childhood the environment is the more important component, but, at the time of adolescence, with the increased production of steroid hormones, end-organ sensitivity begins to play a significant role. This, however, is greatly influenced by the individual's past emotional experiences. When endocrine maturity is achieved in the late teens or early twenties, the psychologic factor becomes, once again, the predominating influence. In the adult human, abnormalities of sexual behavior may usually be considered, in the light of our present information, to be due to psychologic deviations with the hormones playing, at most, a secondary role. Endocrine factors can be of importance only when there is other concrete evidence of endocrine disease.