辈分 (bèifen) is a cornerstone of the Confucian social order, which emphasizes hierarchy, respect, and defined roles to ensure social harmony. It is the practical application of values like 孝顺 (xiàoshùn) - filial piety and the Five Relationships (五伦 - wǔlún), where the relationship between elder and junior is clearly defined. A useful comparison is to the Western concept of a “family tree,” but with enforced rules of conduct. In the West, a family tree is a genealogical record. You might know someone is your “first cousin once removed,” but this rarely affects how you interact. You would likely call your dad's 30-year-old cousin “Steve.” In China, that 30-year-old cousin has a higher 辈分 (bèifen). He is in your father's generation, so you must address him as 叔叔 (shūshu) - Uncle. Calling him by his first name would be a major sign of disrespect, seen as arrogant and poorly raised. This is because 辈分 (bèifen) is not about age, but about your structural position in the family lineage. This system reinforces the collective nature of the family over the individual, prioritizing group harmony and respect for the lineage over personal familiarity.
While modernization has relaxed some social rules, 辈分 (bèifen) remains highly relevant, especially in family settings.