Sigmund Freud emphasized that past experiences, expecially childhood experiences, as critical to the formation of adult personality and behavior?

The adult personality developed by the combination of the experience from childhood both consciously and unconsciously. These experiences shape the personality of a person. Not every person needs to complete their development stage with success. When a person does not complete their stages with success then they developed mental illness.

This type of mental condition needs a theory called psychoanalysis for proper functioning. It is true according to this theory most people suffering are considered because of childhood development. Thus it is determined that childhood experience determines the personality of a person.