Gossip About Children, Sons, Daughters

It's not normal for a parent to gossip about their child with their friends, their partner, other relatives, or their other children.
It's also quite unhealthy to gossip about other people's children, relatives or not.

"He is such a loser, he just takes advantage, he's lazy and shiftless. All he does is sit on the computer. He SAYS he's 'writing' and 'working on a project', yeah sure. Show me the money. He's just trying to get out of working. Eats constantly, like a vacuum cleaner. He has no clue about life! He doesn't even watch Football with the other guys."

Adults who have such a habit are prone to surrounding themselves with other adults who do this too, OR with adults who are happy to scapegoat other people's children, but who put their own on a Pedestal.

A parent with Narcissism will typically either bad-mouth their own child, OR put their own child high above others.

Often, they will bad-mouth one child to others, and put another up on a pedestal.

Narcissistic parents (and uncles, aunts, and others) often create a dynamic of triangulation, suspicion, envy, resentment, shame, aggression, frustration, and dependency in their family. Some members are the "good people" and others are the "losers", at least today.

Next month or next year, who is in the "good club" and who gets left out and scapegoated might change, not according to who is actually "doing well" or "being a good person", but instead who is playing the GAME. Who is kissing who's behind, who is pretending to go along so they don't get targeted anymore, and who has stood up to someone's control or manipulation, or who has stood up for someone else against disrespect. (The latter two would be the ones who get transferred to the "we don't like them anymore" group). 

Other groups of adults who are charged with caring for, mentoring, or teaching children are also vulnerable to Narcissists within their ranks, instigating judgment, gossip, favoritism and rejection toward the children who are supposed be protected and supported.

It's NOT "normal" for adults to gossip about children, nor is it for people to gossip about grown children. VENTING is not gossiping. Seeking advice or support from non-judgmental friends or relatives is not gossiping.
Spreading negative implications or rumors, telling tales, casting judgments, and name-calling behind a person's back IS "gossiping", and is also slander when the gossip damages a person's reputation in the family or community. (When the rumors, namecalling, exaggerating, and false stories makes people think less of the person.)

The difference sounds something like this:

Venting: "I get so frustrated when my daughter turns all the lights on and doesn't shut them off, and leaves the TV on too, it's running up the electric bill. She shuts them off when I tell her to, with an attitude, but then she leaves them on again."
(Friends' response): "I hear you, my son does the same thing. I guess it's because they don't grasp about the cost of utilities yet. I wonder if involving them in the household budget would help."

Gossip/bad-mouthing: "My daughter is such a little princess, she's so spoiled, she thinks she lives in a palace, she thinks I'm her maid. Every time I turn around there are more lights left on, she doesn't care at all. She's such a little snip. I can't wait till she has to pay her own bills, she'll be crying for her Daddy and Mommy then."
(Gossipy friend's response): "You poor thing, that brat must drive you up the wall. I don't know HOW you do it. She must get that Royal Attitude from your husband's side."

Nope, definitely not normal or healthy. Children, both young and grown, who get gossiped and slandered by their own parents, relatives, and "friends of the family" OFTEN end up with emotional difficulties or even temporary mental illnesses from the extremely hurtful and confusing ill treatment, cold-shouldering, and ostracism by groups of people (who are supposed to be their caregivers) who participate in the gossip. They also OFTEN end up with many "real life" difficulties as a direct result of the way those around them treat them. Narcissistic adults DON'T mentor targeted children, they DON'T support them academically, socially, or materially (like non-Narcissistic adults would), and they cause "doors" (opportunities) to be CLOSED instead of OPENED for both young and grown children.
So while children who have been supported by non-Narcissistic adults are happily looking forward to the next opportunity and making the most of the current ones, children (both young and grown) who have been targeted by Narcissistic adults are trying to regain a sense of self, and sense of solid ground under their feet.

Gossipers triangulators usually got a head start during childhood, the habit is often passed down from an adult (or a group of them) somewhere along the line. It's mainly a way to give one's self a sense of false confidence and belonging, or to create a way to control others so they don't leave or so they do one's bidding. But sometimes, for some people, it's just about destruction, manipulation, and domination. 

 Many gossipers and slanderers appear to have some level of delusional thinking or paranoia.