Our understanding of who we are in relationship to the world and other people develops out of the attachment we have to our parent(s) or primary caregiver(s) as children. Parents are often doing the best they can and that can still not be enough sometimes.

As a child, you tell yourself the story that preserves your sense of safety: my parents are good and have it all under control. Safety is a primitive, inherent need you have and your growth as a child depends on it. You're completely dependent on your parents and if they weren't good enough and couldn't provide this sense of safety, the fear would capsize your child self and stunt your emotional and interpersonal development.