Final answer:
Parents are primarily responsible for shaping children's roles, serving as the earliest and most influential agents of socialization. They instill social norms, values, and attitudes that persist throughout life, including influencing political socialization.
Step-by-step explanation:
The family, particularly parents, is primarily responsible for shaping children's roles and is considered the earliest and most important agent of socialization. From infancy, parents teach children social norms, values, beliefs, and attitudes. This includes guiding them on how to behave in social contexts, take care of themselves, and understand their responsibilities within society. The family's influence is profound and persistent and can even extend to political socialization, affecting one's views on topics such as religion, work, and education. While teachers, siblings, and friends do play roles in a child's socialization, the family has the foundational role in training children for adult life, thus setting the stage for all other types of social influences they will encounter later on, including school, peers, and mass media.