Kids Can Stare At People

For reasons I don't fully understand children stare at me. They probably stare at others as well. They might very well stare at any stranger or person with an appearance they consider unusual. It's doubtful that most people are offended by a child's intense gaze and if they were what could they do about it? Anyway, my question is, "When and how do children learn NOT to stare at strangers? I don't remember anybody ever telling me that it's socially unacceptable to stare at someone, although I may have forgotten such an instruction. I've never told my kids not to stare at people, either. This is a subject that deserves some serious study.