The primary childhood influence that leads to narcissism in children is excessive pampering or criticism by a child's parents or other influential adults in the child's life. Even when these parental behaviors occur, the genetics and psychobiology of a child contribute to whether narcissism develops, according to Mayo Clinic. The exact cause of narcissistic personality disorder is unknown, although the cause is most likely complex.
When parents overvalue children by telling them, either overtly or through actions, that they are superior to others and entitled to special treatment, the children are more likely to develop narcissism, notes The Washington Post. Most children who develop narcissistic behaviors by age 12 retain those behaviors as adults. Children's behaviors are most susceptible to parental influence around age 7 or 8.
Parenting techniques that cultivate high self-esteem are sometimes similar to techniques that cultivate narcissism. Parents who show their children warmth and appreciation without creating a sense of superiority often create a sense of self-esteem, while the same sense of warmth and appreciation combined with a sense of superiority can lead to narcissism, notes The Washington Post. However, regardless of parenting techniques, not all children are prone to develop narcissistic behaviors, as the trait is partially heritable.