Is Homosexuality Biologically Determined?

An article in The Philadelphia Inquirer 1 about the book Being Homosexual,2 by Richard A. Isay, a New York psychiatrist and psychoanalyst, led to my reading this short volume. It is a remarkable review of the subject by a physician specializing in treating homosexual men and should be read by anyone with an interest in the subject. Severrd years ago, a geneticist colleague expressed the beiief that sexuality is “biologically determined” and suggested I write an essay on this topic. I’ve been working on it since then, but Simon LeVay’s reeent report in .Science3 has catapulted the idea into greater public awareness. John Maddox, in his inimitable fashion, asked in Nature “Is homosexuality hard-wired?”4 Earlier work by D. F. Swaab in Amsterdam, in Brain Research, s showed that the suprachiasmatic nucleus of the hypothalamus is larger in heterosexual men than in homosexual men. We reprint below an interview with Rockefeller University scientist Bruce McEwen whose research with laboratory animals points to a link between the effects of sex hormones on the brain and sexual motivation. As McEwen notes, knowledge about sexual differences can be important in the diagnosis and treatment of various diseases. The phrase “biologictily determined” can be interpreted in many ways. Homosexuality may be the result of some rdteration in the chromosomes that determine sex. Or, there may be a shift in the fetal endocrine balance as a result of environmental stress in the pregnant mother. But, whatever the reason, most maIe homosexuals appear to lx “constitutionally” gay, and they become May 25, 1992