Can a child become narcissistic coming from a normal home or is it always related to parenting?
No one has the real answer to that one. It could be genetic and learned habits from a parent, or they can acquire this later in life. The label "Nacissist" is flung around far too often and unless a professional has examined anyone then no one else has a right to use arm chair psychology. Narcissism can be mistaken for being a perfectionist, extremely intelligent (acts anti-social and ego-maniacal at times) or could have anger issues. It's best to have a child psychologist speak with your child (alone) and make the diagnosis.
This is just my opinion, but i am under the impression part of the narcissist "suffering" is addictive behaviors. Sex, attention, applause, etc. They cant do without it for one minute. According to some clinical statistics and studies. A high percentage of N's also have co-morbid features, most notably obsessive /compulsive disorders and/or an addiction to drugs, gambling, etc. These traits are considered to be an inherited predispostion - genetic in origin. Makes me wonder if the predisposed genetic material for Naricissism is bundled into some of these chromosomes.
There has been relatively little research into NPD and its genetic origin, if any. Narcissism is very new compared to other disorders which have been studied for decades. Even the statistics vary widely. Some say only 1% of the population suffers from it while other sources say as much as 15% may be affected. The catch is you cant get most narcissists to set foot into a therapist office for a diagnoses for the simple fact they don't think anything is wrong with them. I believe that more than 2% of the population may possess varying degrees of narcissism. But to have a full blown Narcissistic personality disorder is relatively rare. Even that is open to argument because the labels we place on any disorder are higly subjective and really an abstract Human opinion, professional or not.
If you have a child close to you that is exhibiting narcissistc traits please get him some help imediately. First from a medical physician (to rule out any physical defects) and then from a counselor or psychiatrist. The sooner you begin treatment the better. If there is any one time to "cure" a narcisssist it would be in the childhodd /adolescent years. BTW, Narcissism cannot and will not be diagnosed under a certain age, (18 I think) because their personality is not fully developed. So really the "child as a narcissist" point is moot. Just get him some professional help and nip it in the bud.