Instinct

An instinct is a non-acquired tendency.

For example, most humans have an instinctual reaction to feeling threatened, such as fleeing or fighting. Regardless of the actual manifestation in any given event, it is not something we develop out of habit nor something we learn by practice. We can learn to recognize it, our response may change according to context or as we grow and relate to it, and we may even even alter our reaction intentionally, but even the youngest have a base, instinctual reaction to threats nonetheless.