From what I have read in the literature there may be some genetic predisposition that favors narcissistic and borderline conditions, but the predominant factors are environmental, especially the nature and quality of parenting.  There is a lot if indication that it takes both predisposition and bad parenting/bad environment to produce the more notable bad outcomes. And a lot of what may once have been considered genetic may well be epi-genetic environmental programming, including environmental toxins along with behavioral toxins.

If sanity be culturally normative, then by the norms of this culture I claim insanity.