NONFICTION - Nov. 6, 1994

THE SCIENCE OF DESIRE: The Search for the Gay Gene and the Biology of Behavior by Dean Hamer and Peter Copeland. (Simon & Schuster: $23; 272 pp.) “Genes are hardware. They make a person human, produce a penis or a vagina, and allow sexual activity. . . . The software is the difficult part to translate. . . . An IBM operating under DOS can have many varieties, but it will never behave like a Mac. Likewise, some men probably are born with genes that ensure they will be sexually attracted to women--and some to men--all of their lives.” So writes Dean Hamer in “The Science of Desire,” a meticulous, highly engrossing book that, in plain language, explains how the presence of a gay gene was discovered and what it may mean for the future.

In the fall of 1991, Hamer began work on a study funded by the National Institute of Health that used a combination of interviews and sophisticated blood tests to investigate patterns of male homosexuality in families. What he found was nothing short of amazing. Thirty-three out of 40 pairs of gay brothers shared DNA from an area on the tip of the X chromosome--much too high a percentage to be random. Hamer also discovered the gay gene is recessive and passed down through the mother.

It helps when reading “The Science of Desire” to have a rudimentary knowledge of how genes work, but a committed reader can get through without it. Hamer--or perhaps his co-writer, Peter Copeland--displays a real gift for rendering highly complex materials understandable. In addition, many ancillary questions such as why a gay gene might be passed down, and what are the ethical implications of this discovery, are handled in an informative and thought provoking way.