Separate Creation

Burr's detailed, elegantly written report takes us to the front lines of research into a possible biological or genetic basis for homosexuality. He dispassionately reviews the scientific and political controversy surrounding the report in 1991 by gay British neuroanatomist Simon LeVay that a cluster of cells in the brain's hypothalamus is larger in straight men than in gay men. National Cancer Institute molecular geneticist Dean Hamer's 1993 finding that a specific region of the X chromosome is linked to homosexuality in some men led to intense debate over how a ""gay gene"" might function in creating a homosexual orientation. Boston University geneticist Richard Pillard theorizes that the sexual centers of gay men's brains are not ""defeminized""--a hormone-regulated process that routinely occurs in the embryonic brains of male heterosexuals. Burr, whose 1993 cover story in the Atlantic Monthly led to this book, ponders the ethical issues swirling around Affymetrix, a Santa Clara, Calif., company that is building a semiconductor chip made of silicon and human DNA that may make possible widespread testing for a gay gene. Illustrated. Author tour. (June)