During our childhood, until the age of seven years, our brain works in lower frequencies (so-called theta waves). In that stage of brain development, imagination and reality merge together as one. No matter if factually true or not - we store the perceived information/ imagination as true - as how it is, period!
At the same time, we develop a personality from a) the experiences we have made during growing up AND b) by the assumptions we draw from these experiences. And here is the trick, it does not matter if those assumptions about us, others and the world are true or not - in that state of development all input is taken as TRUE and INPRINTED into our identity.
We form a set of unconscious beliefs that accompany us and unconsciously limit us ALL LIFE LONG!
Even though we outgrow our childhood, and the experiences that have once formed these beliefs - we can never outgrow the set of beliefs itself. But we can become aware of and create independent from it!