Sometimes it's cute when kids act self-centered. Yet parenting styles can make the difference between a confident child and a narcissistic nightmare, psychologists at the University of Amsterdam and Utrecht University in the Netherlands concluded from the first longitudinal study on the origins of intense feelings of superiority in children.

Two prominent but nearly opposing schools of thought address how narcissism develops. The first attributes extreme self-love to a lack of affection from parents; the other implicates moms and dads who place their children on a pedestal by lavishing them with praise. Over the course of 18 months, 565 kids aged seven through 11 took multiple surveys designed to measure self-esteem, narcissism and their parents' warmth, answering questions about how much they identify with statements such as “kids like me deserve something extra.” The parents filled out reciprocal surveys about their approach to child rearing.

In a March issue of Proceedings of the National Academy of Sciences USA, the Dutch researchers report that children of excessively praising parents were more likely to score high on narcissistic qualities but not on self-esteem. They also found that lack of parental warmth showed no such link to narcissism.

The correlation shows that positive feedback should be tied to good behavior in a child rather than piled on indiscriminately, says psychologist Luke Hyde of the University of Michigan, who did not participate in the work. A 2008 meta-analysis of 85 studies showed that narcissism is on the rise in young adults in the West, which could stem in part from a cultural emphasis on praise, with the goal of boosting high self-esteem, notes Eddie Brummelman, lead author of the PNAS paper. “It might be well intended,” he adds, “but it actually backfires.”

Such results support the praise-centric school of thought on narcissistic origins, although other scientists in the field point out that controversy still remains over the definition of narcissism itself. Brummelman and his colleagues considered narcissistic personality traits (such as the desire for admiration), not narcissistic personality disorder (characterized by an impairment of daily functioning), in their study because clinicians are discouraged from diagnosing the disorder in youth—no one knows at what age the full-blown psychiatric condition sets in.