[czDRZ-akk]

> Lots of people use 哥, 弟弟, 妹妹, 姐姐 (literally older brother, younger brother, younger sister, older sister) to mean their friendship group, although this is probably a result of the impact of the one child policy.

Use of kinship terms to describe non-kin is clearly not related to the one-child policy given that it’s a language feature of Chinese that occurs across multiple political lines. It also appears in other languages, such as Korean.

Chinese also differentiates kin vs non-kin address. 哥哥 is typically used to describe a blood relation. 哥 and 哥哥 have very different connotations if used to refer to a non-relative.