Confidence

Where does confidence come from? When I was a child I remember thinking adults knew all the answers. As an adult myself, I understand this is most definitely not the case. Is confidence just a way someone presents themselves to the world or is it more based on ego and a primary sense of authority? Working with people and adolescents every day it is remarkable how some people just seem “confident”. It seems hard to differentiate why some people have this trait and others don’t?