New research strengthens the case against soda and other sugary drinks as culprits in the obesity epidemic, adding clout to Mayor Bloomberg's soda ban.

The decades-long study was presented Friday and shows that drinking sugary beverages interacts with genes that affect weight.

Such drinks are especially harmful to people with genes that predispose them to weight gain.

The results strongly suggest that sugary drinks cause people to pack on the pounds, independent of other unhealthy behavior.

Sugar-free drinks, however, did not raise the risk of obesity in these studies.

The studies were published by the New England Journal of Medicine.