Which is NOT typically considered a sibling?

The reason why a cousin is not typically considered a sibling lies in the definition and familial relationships that characterize siblings. Siblings are defined as individuals who share at least one biological or legal parent, which includes brothers, sisters, and half-brothers. Brothers and sisters can share both parents (full siblings) or one parent (half-siblings).

Cousins, on the other hand, are not part of the immediate nuclear family; instead, they are the children of one's aunts and uncles. While they share a familial connection, they do not fall under the same category as siblings because they do not have a direct parental link. Therefore, in the context of family relationships, a cousin is distinct and separate from siblings.