Hereditary rule is not something that is incorporated in the game, nor should it ever be IMO. If we allowed such practice, players could keep their positions forever and there would be almost no turnover anywhere.
well, turnover is easily achieved when you can just grab the land yourself (with your army).. ie.. you are the lord in practice (until someone boot you out with their own army), even if no one recognise it. - obviously not how the game works atm.
if anything i think family should be better structured. ie incorporate a family tree (of a player's making) and i don't mean wiki.