Disciplining young children is what parents are supposed to do most moms and dads have no trouble agreeing with that. But should the punishment include spanking? As many parents can attest, few disciplinary measures stop a child from misbehaving as quickly as a swift smack or two on the bottom. But in a new study published in Pediatrics, researchers at Tulane University provide the strongest evidence yet that children’s short-term response to spanking may make them act out more in the long run. Of the nearly 2,500 youngsters in the study, those who were spanked more frequently at age 3 were much more likely to be aggressive by age 5.