This is an excerpt from Cambridge University Press citing the psychologists who originally studied the origins of NPD. Link to the full article is posted below:
"Theodore Millon's (1981) social learning perspective proposes that children learn about themselves and others from their parents’ behaviour, and in narcissistic individuals, beliefs about specialness and entitlement are thought to stem from early parental overindulgence. Others have pointed to parental abuse and neglect as instrumental in the development of pathological narcissism. Beck described dysfunctional core beliefs or schemas, stemming from early experiences of adverse parenting, associated with NPD that lead the person to be self-indulgent, demanding and aggressive, but also highlighted how these individuals often presented with symptoms of depression (1990)."
