"A recent study adds an important twist to this story. There are the kids with problems with impulse control--"I'm absolutely going to hold out for two marshmallow"--who then instantly eat that first one. That profile is a statistical predictor of adult violent crime. In contrast, there are kids with steep time-discounting curves--"Wait fifteen minutes for two marshmallows when I can have one right now? What kind of fool waits fifteen minutes?" That is a predictor of adult property crime."