User blog comment:B214/Question and Answers 2/@comment-25222726-20140604211452/@comment-24866657-20140604230943

You lack details in your questions, if you're talking about demonic power (mana pool by our standard) then some will inherit while other like Sairaorg is not, but the major of them have to train themselves to reach their parents level. The same things go with demonic ability like Power of Destruction or Phenex Regeneration, depends on the children, for example Sirzechs inherited both Gremory high magic control and Bael Power of Destruction.

Descendant of Satan or the original of the Maou would automatically place them in middle-class, being middle-class just for having the bloodline inside them, they have to train more in order to reach high-class and ultimate-class, if you're talking about Katerae Leviathan then we all know the Old Maou faction loves to boast about what they can do.