Gender: Men are more likely to have this mental health condition than women. nAge: Symptoms of this condition often appear in adolescence and young adulthood. Some children show these traits but do not develop narcissistic personality disorder in the future.nGenetics: You are more likely to develop this disorder if your immediate family members have it.nEnvironment: If you grew up in a home environment where excessive admiration or criticism was the norm, it might lead to this disorder.