Final answer:
The earliest agent of socialization is typically the family, as it profoundly affects social development from birth by teaching societal norms and values.
Step-by-step explanation:
The query regards the earliest agent of socialization in individuals' lives. Out of the options presented, the family is typically considered the first and the most influential agent of socialization. This is because from the very moment of birth, the family begins to impact an individual's social development, instilling societal norms, values, and beliefs. Families provide the initial social context where a child learns to interact with others and understand their position within society.