The demon ancestor perhaps is the generational trauma...angry and impulsive men and the fear of women stealing your descendants... Obviously, a lot of the references to the family devil sound like self deprecating jokes but it still makes you think, this is probably a way people tried to reconcile the frustrations of familial temperamental similarities and patterns of behavior.

Similarly, I have found zero serious academic analysis of this so this will remain an amateur game theory, but it's interesting looking at stuff like Henry II's recorded behavior and how sometimes it reads to me a lot like ADHD -- his inability to sit still, always needing a project to occupy his hands when having meetings, exhausting people by always being on the move/standing and walking around, and being very impulsive and active when touring the kingdom and countryside, to the point where he would give no warning and was hard to pin down, because he would change his mind about his plans all the time. This is all hard to really parse, since this COULD have been a specific strategy to get barons under control, but to me in combination with the other elements it feels very ADHDesque. This, of course combined with his famous temper and impulsiveness that also led to dissolving both longtime friendships and familial relationships, feels familiar as well. I know medieval standards of behavior, and knowing what was real and what was ritual, is hard to tell--but I don't think it's completely out of the question. Such labels of behaviors are constructions that also make us question the "real or ritual" aspects of our own lives, and many of us don't have the lifestyle of kings with attendants, etc etc.

With that being said I wouldn't be surprised if the ND strain was felt in the Devil's brood as well, if not genetically then at least emotionally, through living and dealing with people whose behaviors were affected by it.