A 2001 National Institute of Mental Health report, "Taking Stock of Risk Factors for Child/Youth Externalizing Behavior Problems," showed that it is likely the confluence of mental illness with a variety of environmental or psychosocial factors—low socioeconomic status, poor parenting, and association with gangs are some examples—that significantly increases the chances that a young person will become a violent offender, according to O'Shaughnessy.