In Chinese culture, heavily influenced by Confucian values, age dictates social hierarchy and respect. The concept of 长幼有序 (zhǎngyòu yǒuxù), meaning “order between the old and the young,” is fundamental. Within a family, the 哥哥 (gēge) traditionally holds a position of authority and responsibility, second only to the parents. He is expected to protect and guide his younger siblings. This cultural framework is why the term 哥哥 extends beyond blood relations. Calling a non-related male peer who is slightly older than you “gēge” is not just friendly; it's a sign of respect. It acknowledges their seniority in age, even if by only a year, and places you in a slightly more junior, but still familiar, position. This contrasts with Western culture. While one might call a close friend “bro,” it's a term of peer camaraderie and doesn't carry the same built-in sense of age-based respect. You would not typically address a new acquaintance who is a few years older as “older brother” in English; in Chinese, this is a common and polite way to build rapport.
哥哥 (gēge) is an extremely versatile term used in many daily situations.