A new study indicates that one contributing factor to childhood obesity may be a lack of certain pieces of DNA. One specific deletion, on chromosome 16, found in less than 1 percent of the children who participated in the study, removes a gene that the brain uses to handle the hormone leptin, which governs appetite. These children, says Dr. Sadaf Farooqi of Cambridge University, are "very, very hungry" and "have a very strong drive to eat." The researchers, armed with the findings of their study, were able to intervene in cases of children missing that gene whose parents had been blamed by British child-welfare authorities for overfeeding their children. "It's a slightly unusual outcome of our research, but one we think is very important," said Farooqi.