I have posted articles on this blog about how our beliefs are formed by things we learn from out parents, teachers, friends and our society in general.  This does not mean that we should go through life blaming others for everything we don't like about ourselves or the circumstances in which we live.  
   If we go through life thinking "I can't control my spending because my teachers never taught me how to use money sensibly", "I can loose weight because I come from a family of fat people",  "I can't be a successful artist because my forth grade art teacher said my art was lousy" than we are stuck with what we are.  We can't go back to our childhood and change our parents.  We can't change the opinions of teachers who, by the way, are usually only qualified to judge whether or not you completed the assignments correctly and not to make more general judgments about your skills and talents.  We can't change those childhood friends.  Even if we can, we don't have the right to change other people, we can only suggest they change themselves.  What we can do is change ourselves.  We can change what we believe about ourselves, but only if we stop blaming others.