It's thing called an inner voice. A psychological matter.
When a human is a child that inner voice is usually the mothers. It this a them in what is right and what is wrong. What to do.
Some of us wouldn't see it this way. We all internalise various beliefs - some coming from others - but mainly when we are an autonomous individual we just own our beliefs - which form, as mentioned about choices, from accepting or rejecting that which we input to our minds - and no outside source or authority required. Have you read Julian Jaynes book - well worth a read concerning your point.