Finger length could provide a clue to a person's sexuality, a study conducted by the University of Essex has suggested.
The study looked at sets of identical twins where one was heterosexual and the other was homosexual, and found that the homosexual twin had a greater difference between the length of their index and ring finger.
The study observed that in 18 sets of female twins, the homosexual twin had more "male-typical" hands than her straight sister.
In 14 sets of male twins the gay twin had slightly more "male-typical" hands than their straight brother but the difference between the two was not viewed as significant.
Previous research has indicated that exposure to the male hormone testosterone in the womb could be linked to differences in finger length.
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Women's index and ring fingers are typically of similar length while in men there is a greater difference.
Dr Tuesday Watts, from the department of psychology, said: "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 or the way our individual bodies react to that hormone, with those exposed to higher levels of testosterone being more likely to be bisexual or homosexual.
"Because of the link between hormone levels and difference in finger lengths, looking at someone's hands could provide a clue to their sexuality."
The findings have been published in the journal Archives Of Sexual Behaviour.