Center of Excellence in Behavior Genetics, Department of Psychology, Abo Akademi University, 20500 Turku, Finland. pekka.santtila@abo.fi
We investigated the potential to engage in homosexual behavior in 6001 female and 3152 male twins and their siblings finding that 32.8% of the men and 65.4% of the women reported such potential (p<0.001). 91.5% of these men and 98.3% of these women reported no overt homosexual behavior during the preceding 12 months. The potential to engage in homosexual behavior was influenced by genetic effects for both men (37.4%) and women (46.4%) and these overlapped only partly with those for overt homosexual behavior.