A study from the University of Essex suggests that finger length may offer clues about a person's sexual orientation. Researchers examined sets of identical twins where one twin was straight and the other was gay or lesbian, finding differences in the ratio between index and ring finger lengths.
The study involved 18 pairs of female twins and 14 pairs of male twins. In the female pairs, the lesbian twin typically had a greater difference in finger lengths—a trait more common in males—compared to her straight sister. Among male twins, the gay twin also showed slightly more 'male-typical' hand characteristics, but the difference was not statistically significant.
Previous research has linked finger length differences to prenatal exposure to testosterone. Women generally have index and ring fingers of similar length, while men tend to have a larger difference. Both sexes are exposed to testosterone in the womb, and higher levels are associated with a greater likelihood of bisexuality or homosexuality.
Dr Tuesday Watts from the university's psychology department explained: 'Because identical twins, who share 100% of their genes, can differ in their sexual orientations, factors other than genetics must account for the differences. Research suggests that our sexuality is determined in the womb and is dependent on the amount of male hormone we are exposed to.'
The findings have been published in the journal Archives of Sexual Behaviour.
