Childhood misconceptions seem kinda outside the purview of this thread but OK: when I was a kid, I used to think parents could read the minds of their children. This was reinforced when I learned about how babies are made; if adults could keep that a secret, surely they could hide a mind-reading conspiracy. I figured that this is why adopted children and bastards were often represented in the media as having a poor relationship with their guardians, because they didn't have anyone that could truly understand their feelings and thoughts. I believed that until I was about 14 or so, and used to always brainwash myself when near my parents so that they wouldn't get suspicious.