“Thank God toddlers don’t carry guns.” On the roots of violence.

My latest at the New York Times looks at the work of child psychologist Richard Tremblay, who finds that violent criminals don’t become violent — they just stay that way.

To understand the violent criminal, says Richard E. Tremblay, imagine a 2-year-old boy doing the things that make the terrible twos terrible — grabbing, kicking, pushing, punching, biting.

Now imagine him doing all this with the body and resources of an 18-year-old.

You have just pictured both a perfectly normal toddler and a typical violent criminal as Dr. Tremblay, a developmental psychologist at University College Dublin in Ireland, sees them — the toddler as a creature who reflexively uses physical aggression to get what he wants; the criminal as the rare person who has never learned to do otherwise.

In other words, dangerous criminals don’t turn violent. They just stay that way.

How so? They fail to get civilized, as Huck Finn might put it. And in this, Richard Tremblay sees opportunity. Get the whole thing at Terrible Twos Who Stay Terrible, at The New York Times Mind column