Final answer:
George's behavior is best explained by Differential association theory, which indicates that he learned criminal behavior through close interactions with his brother and the gang.
Step-by-step explanation:
The concept that best explains George's behavior as a career criminal after having been influenced by his older brother and becoming involved in a criminal gang at a young age is A) Differential association theory. Developed by sociologist Edwin Sutherland,
differential association theory suggests that criminal behavior is learned through interaction with others, particularly those we are close to. The theory posits that individuals learn the values, attitudes, techniques, and motives for criminal behavior through interactions within intimate personal groups.
In George's case, his brother Jake provided a model for deviant behavior, which George learned and eventually normalized as part of his lifestyle.