Genetic Clue to Male Homosexuality Emerges
Bower, Bruce, Science News
Researchers say they have taken a major stride toward identifying a gene that may importantly influence the development of some cases of male homosexuality. The new evidence, published in the July 16 SCIENCE, suggests that a gene lying within a small stretch of the X chromosome, inherited by men from their mothers, contributes to the sexual orientation of a subset of homosexual men.
"We haven't identified the gene yet, and any theory of how it works is speculative," asserts Dean H. Hamer, a geneticist at the National Cancer Institute in Bethesda, Md. who directed the study,
However, a gene wedged into a tiny segment of DNA -- containing perhaps as few as several hundred genes -- probably performs functions linked directly to sexual orientation, Hamer proposes.
Other investigators have proposed that an individual's sexual orientation depends on the interplay of culture, family, hormonal influences, and inherited personality traits.
"If Hamer's data are replicated, this will be the only linkage of a gene to a high-level function performed by the [healthy] human brain," says psychiatrist Elliot S. Getshort, chief of the clinical neurogenetics branch at the National Institute of Mental Health, also in Bethesda, Md.
The failure of different scientific teams to confirm reports of genes linked to schizophrenia (SN: 11/12/88, p.308) and to manic depression (SN: 3/28/87, p. 199) illustrates the importance of independent replication, Gershon notes.
Hamer's group recruited 114 men who met a strict definition of homosexuality. Participants described themselves as gay, felt sexually attracted to other men, fantasized mainly about men, and engaged in sex always or mainly with men.
Hamer and his co-workers estimate that 2 percent of all men and women meet this strict definition of homosexuality, although generally accepted figures for the prevalence of male homosexuality range from 4 to 10 percent. …