It's shown that spiritual powers run in families. And that the types of power that a human can have varies- Chad, Orihime, the Fullbringers, whatever was going on with Ururu and Jinta. So why is it that beyond seeing ghosts, only Quincy/Shinigami powers seem to get passed on from generation to generation?
Beyond the whole "Karakura is the setting" thing, why do we not even hear about this being possible? Shinigami patrol the Living World: would they not have even rumors of this (at least among Division 12)?