My younger cousin has been smart since she was little.
Tips
usage
Chinese has specific terms for every type of cousin. 表 cousins have different surnames (mother's side, father's sister's side). 堂 cousins share the same surname (father's brother's side). 妹 means younger, 姐 means older.
culture
The full set of female cousin terms: 表姐 (older, different surname), 表妹 (younger, different surname), 堂姐 (older, same surname), 堂妹 (younger, same surname). This system reflects the importance of family lineage in Chinese culture.