Or, if in the past the families decided to utilize such “esp” tendencies to take advantage of others... the bloodlines might tend to be not so loving?
Carrion Comfort by Dan Simmons is about rich people using esp for evil. They suck energy from other people when they do it. They were using esp to get other people to commit horrific crimes. There’s even an island in the story where people are hunted down and they have people stored in caves underground. Very Little St James...
When I read the book it reminded me of the bloodline families and Epstein’s island.