Allies and persecutors: science and medicine in the homosexuality issue.

Using Magnus Hirschfeld (1868-1935) and his Zwischenstufentheorie (theory of intersexual stages) as an example, the problems raised for homosexuals by etiological research into homosexuality are scrutinized. Hirschfeld, one of the most influential sex researchers working in the first part of the century, fully intended his biological theory to support his campaign on behalf of homosexuals' rights. However, the Zwischenstufentheorie and modern variations of it, such as the ideas of the endocrinologist, Günter Dörner, have been converted into strategies for preventing or curing homosexuality. From an historical point of view, it becomes clear that, in a society hostile to homosexuals, the results gained from research into the causes of homosexuality can be used against homosexuals and, in fact, have been.