Role of genetic factors in human sexual behavior based on studies of Tourette syndrome and ADHD probands and their relatives.

Most significant variations in the expression of human sexuality are considered to be the result of learned behavior or psychological problems. Tourette syndrome (TS) is a common, hereditary tic and disinhibition disorder sometimes associated with compulsive use of obscene words (coprolalia) and previously reported to be occasionally associated with exhibitionism. To further explore the relationship between the Gts genes and sexual behavior, questions concerning a wide range of such behaviors were administered to 1,040 subjects, 14 years of age or older, consisting of 358 TS probands, 101 non-proband relatives with TS, 359 non-TS first degree relatives, 79 attention deficit hyperactivity disorder (ADHD) probands, 70 unaffected relatives of the ADHD probands, and 73 controls. The behaviors included magnitude of sex drive, sex orientation, exhibitionism, transvestitism, transsexualism, sadism, masochism, pedophilia, fetishism, aversion to being touched, and aversion to sex. While most of these behaviors occurred in a distinct minority of TS subjects, there was a significant positive correlation between each behavior examined and the degree of genetic loading for the Gts gene(s). The nature of these behaviors and their association with TS suggests many are variants of obsessive-compulsive disorder. Studies in animals indicate that changes in serotonin and dopamine play a significant role in the sexual behavior and many lines of evidence are consistent with the hypothesis that TS is due to genetic changes in serotonin and dopamine metabolism. These studies suggest that genetic factors play a much greater role in a wide range of forms of sexual expression than previously thought.