NPD is an inherited disorder (as well as acquired). It runs in families. Here is how it shows up in my family (immediate family shown only, as I do not know my extended family too well, thanks to my MN mother’s manipulations to keep me from them).

People raised in NPD families also have an unfortunate tendency to marry or enter into relationships with other people with NPD, and my family tree definitely shows this tendency.

My NPD Family Tree

Paternal grandparents: Grandmother (no NPD); Grandfather (possible NPD) —-> Father (low spectrum NPD); 1 other son (no NPD)

Maternal grandparents: Grandmother (possible NPD); Grandfather (possible NPD) —-> Mother (MN=malignant narcissist); 3 other children (unknown if any of them have NPD)

My mother: MN; my father: low spectrum NPD and enabler —–> 5 children from 2 marriages each (1 deceased): my mother’s oldest daughter is her most loyal flying monkey and probably NPD; I don’t think my other half-siblings have the disorder (they were raised with at least one non-NPD parent); I was the only scapegoat and have Avoidant PD, which is the polar opposite of NPD.

Me (no NPD); Michael (NPD, possibly MN) ——>; 2 children: son Ethan (scapegoat and non-NPD); daughter Molly (NPD, probably not MN)

Michael’s immediate family:
Mother (MN); father (non-NPD but an enabler and absent much of his childhood) —–> Michael (NPD, possibly MN); 1 sister (non-NPD but abused by her NPD husband)