What factor does NOT contribute to shaping trends in juvenile delinquency?

The age of onset refers to the age at which individuals begin to engage in delinquent behaviors. While it can influence the trajectory or pattern of delinquency over time, it is not a direct external factor that shapes trends in juvenile delinquency. Trends in juvenile delinquency are typically shaped by social, economic, and environmental factors, rather than the individual characteristics such as the age at which a person begins offending.

Factors like drug use, availability of guns, and crime control policies play significant roles in influencing rates of delinquency. For instance, increased drug use among youth can lead to higher rates of delinquent behavior, while the availability of firearms can escalate violent crime rates among juveniles. Additionally, crime control policies can change law enforcement practices and the legal consequences for youth, directly affecting patterns of delinquent behavior. In contrast, the age of onset doesn't directly cause shifts in these wider societal trends, making it the least impactful factor in this context.