Poor nutrition, inadequate health care, prenatal exposure to illicit substances, and inadequate sleep all interfere with proper brain maturation, hindering social and cognitive development. Moreover, a number of genes have been identified that are associated with reckless, poorly controlled behavior. Finally, biologically based mental conditions, such as attention deficit disorder and various learning disorders, also interfere with behavioral control and raise the risk of criminal behavior.
One study found that violent men whose heart rate went down during an argument with their wives had higher levels of aggressive-sadistic tendencies (iStock).