Male twins gay sex

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Archives of Sexual Behavior. Twin pairs in which at least one twin is homosexual were solicited through announcements in the gay press and personal referrals from to the present. Thirty-eight pairs of monozygotic twins 34 male pairs and 4 female pairs were found to have a concordance rate of Twenty-three pairs of dizygotic twins were found to have a concordance rate of

A new study of twins provides the strongest evidence yet that homosexuality has a genetic basis, researchers say, though they say other factors like social conditioning may be important. The study, published in the December issue of The Archives of General Psychiatry, adds to evidence that sexual orientation does not result from a maladjustment or moral defect, one author said. Michael Bailey, an assistant professor of psychology at Northwestern University in Evanston, "which is exactly the kind of pattern you would want to see if something genetic were going on. Bailey was referring to brothers by adoption.

A genetic analysis of pairs of gay brothers, including sets of twins, has provided the strongest evidence yet that gay people are born gay. The study clearly links sexual orientation in men with two regions of the human genome that have been implicated before, one on the X chromosome and one on chromosome 8. The finding is an important contribution to mounting evidence that being gay is biologically determined rather than a lifestyle choice. The region on the X chromosome picked out by the study, called Xq28, was originally identified in by Dean Hamer of the US National Institutes of Health in Bethesda, Maryland, but attempts to validate the finding since have been mixed. The other region picked out is in the twist in the centre of chromosome 8.