What your parents told you is what's really going on "It's all in your head." Humans love to receive unfamiliar or vague instances and personify them in an attempt to evoke familiarity, which is why simple breezes can be misinterpreted as "voices," and small corners of low light can appear to be "shadow figures." Also, as for things tipping over, while this doesn't account for all instances of things falling by themselves, magnitude three or under Earthquakes can are virtually undetectable by people, but can still cause such things to happen. The mind is wonderful at deceiving the body it's in.