Just as education and aspirations were 'normalized' for Gary G., criminal behaviors were normalized for Gary F. At a very young age (Burkhead 2006: 24). Also, there may be genetic factors which predispose certain individuals to aggressive behavior which makes them more susceptible to crime. This was combined with evidence of a genetic tendency towards addiction in the form of alcohol. His mother was very ambivalent about having a child and there may have been some developmental problems caused because of a lack of prenatal care. Gary G.'s home environment was extremely chaotic and he had no stable caregivers. He also sustained a trauma to the head at a young age, and concussions and early head injuries are linked to asocial behavior (Burkhead 2006: 24-25). There was little institutional support for Gary F. He did not go to preschool, and a possible learning disability was undiagnosed and untreated in his chaotic school system (Burkhead 2006: 24). He was exposed to alcohol very early in life and drinking was quickly 'normalized' for him as acceptable behavior. He began smoking and engaging in sex very early in life, due to his unsupervised existence. Although he tested as having above-average intelligence, he had no 'advocates' within the system in the form of teachers or coaches because he did poorly in school, he did not participate in extracurricular...

With no role models or viable career prospects, Gary F. quickly fell into a life of crime. He dropped out of school and began selling marijuana (Burkhead 2006: 24).
Thus, one clear risk factor for criminal behavior is early drug use, given that Gary F.'s habit provided a springboard for his first lucrative criminal activity. From Gary F.'s perspective, crime did 'pay' in the short run, since the example of his family and the world around him suggested he would make more money selling drugs than going to college and getting a traditional job. There is also strong evidence of a genetic link that makes particular individuals susceptible to addiction and Gary F. came from a household of addicts, including his biological mother (Burkhead 2006: 23-24).

But not everyone who uses drugs early becomes an addict -- Gary F.'s lack of exposure to other ways of life and lack of positive reinforcement to succeed in school made selling drugs seem more attractive than someone with a great deal to lose, like Gary G. Even genetic factors can become more likely to be expressed in some environments than in others. Even if Gary F. may have had problems with alcohol addiction due to his genetic makeup, because of his class, income level, and environment, he had little access to rehabilitation programs.

Reference

Burkhead Michael, Dow. (2006). The search for the causes of crime: A history of theory in criminology. McFarland & Company.