Before you make a comment, please research the boundaries of the oceans.
Here is a good place to start:
(Reminds me of somerhing, not exact comparison though. But I can imagine a little kid saying about a person, no she isnt a daughter or a sister, but she is my mother. (In kid language, like laughing like you are very silly to suggest she is a daughter, "no that's mommy") It takes such precedence in his mind, that he cant imagine her being something else too, she is his mother and that's that.)