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Twin studies and homosexuality.
If there is something in the genetic code that makes an individual homosexual, why did not all of the identical twins become homosexual since they have the exact same genetic endowment?
Some comparative data on twin studies show similar correlations with (socially determined?) factors: extroversion, religiosity, divorce, racial prejudice and bigotry. One has to conclude that environmental influences play a strong role in the development of homosexuality. 52 percent of identical twin brothers of gay men also were gay, compared with 22 percent of fraternal twins, compared with 11 percent of genetically unrelated brothers (brothers by adoption), which is exactly the kind of pattern found where something genetic is going on. The genetically most similar brothers were also the ones most likely to be gay, by a large margin. Twin studies and homosexuality.
