ABSTRACT
Twin studies also have been used to examine the heritability of homosexuality. The concordance of homosexuality is considerably higher among monozygotic twins than dizygotic twins-20% to 24% compared to 10% or less (Hyde, 2005b). This difference applies to both gay men and lesbians. However, if one identical twin is homosexual, the chance that the other identical twin is homosexual is far from 100%.
