Wrong habits and mistakes made in early childhood.
Repeated and severe suppression of the emotional and communicative development urge during early childhood and adolescence.
Repeated and strongly emotive suppressing of inhibitive experiences, negative and disappointing life events and the confrontation of inhibiting thoughts.
Frequent, obsessive, dealing with negative and inhibitive thought patterns.
Frequent and especially strong emotive disgraces, embarrassments, and humiliation.
Feelings of shame and guilt, especially during puberty.
However, people are not only "trained" during childhood but are influenced and molded throughout their lives.