Researchers today don’t know what causes NPD. There are many theories, however, about the possible causes of narcissistic personality disorder. Most professionals subscribe to a biopsychosocial model of causation — that is, the causes are likely due to biological and genetic factors, social factors (such as how a person interacts in their early development with their family and friends and other children), and psychological factors (the individual’s personality and temperament, shaped by their environment and learned coping skills to deal with stress). This suggests that no single factor is responsible — rather, it is the complex and likely intertwined nature of all three factors that are important. If a person has this personality disorder, research suggests that there is a slightly increased risk for this disorder to be “passed down” to their children.