Murray Straus, co-director of the Family Research Laboratory at the University of New Hampshire, has done extensive research on domestic abuse, and he has reached a judgment about spanking of kids. “One simple way of putting it,” he told me, “is that all the effects of corporal punishment are bad.” More than 100 studies, he said, establish that it increases the likelihood that recipients will engage in violence as children and as adults.

One of the most arresting charts in his book, “The Primordial Violence,” shows the relationship between spanking and murder among the 50 states. Most kids who are spanked don’t grow up to be killers. But as the caption says, “The larger the percent of the population who approve of spanking, the higher the homicide rate.”

Internationally, more spanking correlates with more murders. Adults who were spanked are more likely to assault spouses or romantic partners than adults who were not. Kids who are hit by parents are prone to hitting other kids.

_These correlations are not accidental. “Spanking teaches that it’s morally correct to use violence to correct misbehavior,” Straus explained. Someone who absorbs this vivid lesson, confronted with objectionable conduct, is more likely to resort to force to stop the conduct.