1.   Biological (genetic & health related) factors
         2.   Psychological (perceptual, cognitive, emotional & personality) factors
         3.   Sociocultural (interpersonal, societal, cultural & ethnic) factors
         4.   Life-cycle (same event produces age-dependent effects) factors

B.     Nature-Nurture

         1.   Sole Cause
         2.   Interdependent Causes