Psychiatrists studying the eating disorder reviewed records of Swedish twins, finding the risk of developing anorexia was higher in girl twins than in boy twins, The Times of London reported.

Claims that girls who become anorexic were influenced by images of rake-thin models weren't disproved by the University of Sussex study. It did suggest, however, that genetics may be involved.

Marco Procopio, one of the study's authors, said health professionals know women are more likely to develop anorexia "and this study goes a long way to explaining why."

He noted that estrogen and other hormones "can have a powerful effect on the body and it would seem that there is an 'over-expression' of estrogen by the mother and the girl twin in some pregnancies."

While estrogen is needed in development of females, "it is possible that too much affects the structure of the brain." Procopio said.

The study supports U.S. research finding that the brains of anorexics behaved differently.

The findings appeared in the latest edition of Archives of General Psychiatry.