Family Trees: random or not?

[bugrat]

I am playing my third EB campaign and I'm wondering if family trees beyond the people who are part of the family at the start of the campaign are randomly generated or are based on real people (or any combination of the two).

I was playing Carthage and was curious about it, I was going to try to find out for myself but old Hannibal's daddy was killed by mad rebels one season before the boy was supposed to be born hehe.

EB rocks!