Almost immediately the foundations of the hereditary theory were threatened. For Freud’s thesis, as no one needs reminding in this generation, was that the human personality passes through several phases of sexual development, beginning in earliest infancy, and reaching maturity only with complete heterosexual experience. All individuals, he said, are potentially bisexual. In some, the homosexual component becomes conscious and active, and unless this phase gives way with the passing of adolescence to the heterosexual, the personality remains arrested and immature. Such an arrest constitutes neurosis, whether or not it becomes troublesome enough to demand psychiatric attention. As is obvious, this view contradicts the hereditary theory at several important points. It holds that the homosexual is not born, but made by conditioning factors in his early life, chiefly family relations before he is five years of age. He can usually overcome his neurosis if he earnestly wishes, at least with the aid of psychiatry; therefore, he may be considered more or less responsible for his state if he persists in it. Furthermore, the bisexual is nearer to maturity than the homosexual. This conclusion is particularly opposed to the tenets of the Ellis-Hirschfeld school, which classed frigidity to the opposite sex as a mark of “true,” that is, innate and blameless, homosexuals. The battle between the hereditary and the Freudian theories can be detected in a good deal of twentieth-century variant fiction. The pendulum swung again toward physical causation with the development of endocrinology, which at first held the individual’s glandular endowment responsible for his sexual inclinations. This science began as a branch of general physiology, and acquired major sexual importance only with Steinach’s and Voronoff’s famous experiments in rejuvenation through graft of sex glands or other reinforcement of sex hormones. In the variant field, endocrinologists were first concerned with glandular influence on secondary sex characteristics—breast development, hair distribution, vocal register, et cetera. Thus, during the 1920s and 1930s a number of physicians were attempting to cure homosexuals by dosing them with hormones which reinforced their biological sex and tended to decrease variant traits. These experiments enjoyed some publicity in medical literature but had only limited success. In the meantime, disciples of Freud were bringing in evidence that psychological disturbances alter endocrine balance. The final compromise is the current school of psychosomatic medicine.