Gene Linked to Social Behavior British scientists say they have found evidence of a gene that seems to make girls superior to boys at winning friends and knowing how to behave in social situations. Young girls with a rare genetic disorder called Turner's Syndrome were studied. The cause of Turner's syndrome is unknown but is related to abnormal chromosomes. Instead of having two normal X, or female chromosomes in each cell, the girls have one normal and one broken X, or sometimes just a single normal X, with the other missing. This leads to an inability to "read" other people's tone of voice, body language, and other subtleties which can lead to rejection. The researchers used questionnaires filled out by the girls' parents to rate their social competence. Those rated as socially inept tended to be those with an X chromosome from their mother, while those with normal social skills had an X inherited from their father. The findings fit with their hypothesis that a gene for social cognition is located on the X chromosome, but is "switched off" when it is passed from a mother to her son and "switched on" when passed from a father to his daughter. (Boys inherit their single X chromosome from their mother; girls inherit one X from each parent.) According to the British researchers' theory, girls' brains are "hard-wired" to pick up social skills" almost instinctively," while boys have to work hard to learn them. Boys are also more vulnerable to autism and other behavior disorders because the silent "social behavior" gene on their X chromosome interacts with other unknown genes that underlie these disorders.