“…in The Crime Drop in America, edited by Al Blumstein and Joel Wallman. They rounded up the usual suspects – the solid economy, new police strategies, the incarceration boom, the stabilization of drug markets, anti-gun policies. But we all missed something important – lead. Children exposed to high levels of lead in early childhood are more likely to have lower IQs, higher levels of aggression, and lower impulse-control. All those factors point to crime when they reach their teens if not earlier.