Do We Have This One?? This is for the notion that people are often expected to be like family members (especially parents or siblings) yet are often more different from them than expected. Examples include, aside from the above School Study Media example, an Arthur episode where people expected Mr. Ratburn's sister to be as tough as him if not tougher, only to later find out she was a Misplaced Kindergarten Teacher.
Hello, Unknown Troper. You'll need to get known to lend a hand here.