I am glad you understand, thanks, Fifi. (and actually, British and American culture are two very different things as well...)
I just dug this up in the second of your links above. It says, empathy failing to develop in a child comes from having caregivers lacking in empathy...there is also a genetic predisposition. I find the last sentence especially interesting.
copy:

"The leading theory about the development of NPD is that people get it the old-fashioned, Freudian way: Your parents give it to you. It starts very early when the attachment between infant and caregiver goes awry. In the first years attentive parents instinctively respond to the infant's moods. But cold, neglectful, or abusive parents don't provide the necessary comfort. Paradoxically, over-involved parents can be just as damaging because they convey anxiety and distress in the face of their child's unhappiness. As a result of neglect or smothering, these children don't learn the essential skills of being able to soothe themselves and regulate their feelings. The authors of The Narcissism Epidemic say the drift toward hovering, boosterish parents who want to gratify their child's every impulse will churn out more narcissistically disordered people.

Fortunately, not everyone with this kind of parenting ends up with NPD, which indicates there is a genetic susceptibility as well. Harvard's Ronningstam, in her book Identifying and Understanding the Narcissistic Personality, cites evidence that hypersensitive babies with a low tolerance for frustration and a strong aggressive drive may be particularly vulnerable.

Because the caregiver lacks an empathetic understanding of the baby, the baby's ability to become an empathetic person is impaired. Empathy, the ability to instinctively understand how another person is feeling, is a crucial human attribute, part of what makes us a social species. A chilling lack of empathy is a hallmark of NPD. Shame, that painful sense one has acted in an unacceptable way, is another necessary emotion that is also largely missing from the person with NPD. Since shame feels so terrible, it sounds liberating not to feel it. But psychologist Schore points out a feeling of shame signals that we need to reassess our behavior. "Shame is a moral emotion," he says. "It's without feeling shame that the most horrendous acts occur."

Those involved with someone with NPD frequently say they feel as if they are interacting with a kindergartener. In some way they are. According to a study in the journal Advances in Psychiatric Treatments, narcissists are stuck with the emotional development of 5-year-olds. It's about at age 5 that children start realizing their feelings are not just the result of other people or events but occur within themselves, and that they have control over them. But this understanding does not take place for the narcissist, who continues to see all internal states as having an external cause. Because of narcissists' inability to control their own emotions, they unconsciously experience the world as constantly threatening—thus the tendency toward inexplicable rages, the wild overreactions to the slightest perception of criticism."