That is a complex question. Narcissistic personality disorder (NPD) is a complex condition that may be comorbid with other affective and personality disorders. The roots of NPD tend to reach back into childhood. The disorder itself may be diagnosed after age 18. A combination of multiple factors—environmental, social, genetic, neurobiological—likely play a role in formulating a narcissistic personality. There is evidence that NPD is heritable, and individuals are at a higher risk of developing the disorder if there is a family history of the disorder. Cultural elements are believed to influence the prevalence of NPD as well, since NPD traits have been found to occur more frequently in modern societies than in traditional ones.