Narcissism is a mental condition that can be caused by a number of factors, including:

Genetics

People with narcissistic personality disorder (NPD) are more likely to have close relatives with the condition.

Observation and imitation

Children can learn narcissistic traits and behaviors from observing and imitating others.

Negative childhood experiences

There may be a link between NPD and negative childhood experiences.

Parenting style

Overprotective or “helicopter” parenting, or overindulging children, can lead to children who expect and demand the same treatment from others.