Children, for the most part, are all given the same basic knowledge. We're taught how to tie our shoes. We're taught how to dress ourselves, our alphabet, the "correct" amount of milk to pour in a bowl of cereal. We're taught to shampoo our hair before we condition it. We're taught how to brush our teeth.
These basic, mundane activities that many of us do on a daily basis eventually get taken for granted. We do them on auto-pilot without much thought and there's an assumption that there's nothing really all that special about them. But the thing is, these activities are learned behavior, and learned behavior is taught slightly differently from person to person.
So when you put these mundane activities under the microscope and see how differently people go about doing them, you realize that we've developed ideas on the "right" way of doing something, just because that's what we've been taught and we've been doing it all our lives. A fact that's surfaced when one Twitter user posed this seemingly innocuous question: