Narcissists And Children

An adult with Narcissism who has direct access to a child can wreak havoc on the child's self-esteem, on confidence in her or his own abilities, and on the child's belief in his or her own ability to LEARN and achieve.
An adult with Narcissism who has direct access to a child can wreak havoc on a child's belief that he or she is a good person, and on the feeling that he or she belongs, or deserves to be a member of the group at all, either the small groups the child is a part of (including family), or larger groups, such as sports, dance, or music lesson groups, classes or school in general, the community in general, the child's/ family church, synagogue or other religious gathering group, or the larger human family group.
Narcissistic adults tend to treat children like objects that are there to be judged, as open targets for criticism, as burdens on their lifestyle and resources, as unpaid servants, and as objects to use for their own agendas.

The level of psychosis an individual Narcissist is afflicted with is what dictates the level of abuse or neglect they inflict on children. Some Narcissists are abusive "only" verbally and emotionally, while those with more severe psychosis may wantonly sabotage, gaslight, terrorize, slander, or physically abuse a child. 

Narcissists are not always who we think they are, and they are quite often who we think they are NOT. 
Honest observation of others and ourselves, and open communication are the required tools to discern Narcissists from non-Narcissists. It's very difficult because most humans in modern culture are conditioned during childhood to turn a blind eye to it, and to buy into the glossy, or "responsible", or good-person facade that Narcissists tend to use as an image.