Explain the concept of persistent offenders.

About two-thirds of substance-abusing youths continue to use drugs in adulthood, but about half desist from other criminal activities. Those who persist in both substance abuse and crime maintain these characteristics:
 They come from poor families.
 Other criminals are members of their families.
 They do poorly in school.
 They started using drugs and committing other delinquent acts at an early age.
 They use multiple types of drugs and commit crimes frequently.
 They have few opportunities in late adolescence to participate in legitimate and rewarding adult activities.
 Some evidence exists that these drug-using persisters have low nonverbal IQs and poor physical coordination. Nonetheless, there is little evidence to explain why some drug-abusing youths drop out of crime while others remain active.