Paarthurnax can't say he has too much experience with mortal families, not for many many years at any rate. He simply knows what is expected of them- the general idea of it.

"Two things happened. One of the first was that my brother, worshipped and filled with power as he was, began to consider himself on parr with the Gods as well. Such a thing... I had always known my brother to be full of pride, but I had not realize he had deluded himself to such an extent." Another sigh, this one more disappointed than anything. "The second to happen... was that those mortals we had counted as mere slaves began to fight back. They wanted freedom- not to slave away under an empire that viewed them as nothing."