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 In addition, three sets of triplets were obtained.
Why Do Some Identical Twins Have Different Sexual Orientations?
Your Good Health: Why is one ‘identical’ twin gay, the other straight? | Times Colonist
A growing amount of research suggests that sexual orientation has a genetic basis. In fact, scientists recently identified two specific genes that appear to differ between gay and straight men . If sexual orientation is indeed genetically determined, it would be tempting to assume that identical twins would always have the same orientation, right? If they have the exact same genes and our genes control our sexuality, this would seem like a pretty logical conclusion. Identical twins sometimes have different orientations. For example, one may be straight while the other is gay.
Homosexual orientation in twins: A report on 61 pairs and three triplet sets
Dear Dr. Roach: I read your recent column regarding identical twins where one of the two was balding while his twin was not. Within my extended family, there are identical twin brothers, who also were almost impossible for family members to differentiate.