traits associated with narcissistic personality disorder

What makes these trait a true personality disorder is that they take over people's lives and cause significant problems.Imagine that instead of caring for your spouse or children,you used them as a source of attention or admiration.Or imagine that instead of seeking constructive feedback about your performance,
you instead told everyone who tried to help you that they were wrong.So what causes narcissism?Twin studies show a strong genetic component,although we don't know which genes are involved.But environment matters, too.