The researchers concluded this after monitoring more than 1,000 children from birth to 32 years of age.

Moffitt TE, Arseneault L, Belsky D, et al. A gradient of childhood self-control predicts health, wealth, and public safety. Proceedings of the National Academy of Sciences of the United States of America. 2011;108(7):2693-2698. doi:10.1073/pnas.1010076108.