Wherever you read it, The Cleanest Race is probably the source. It is orientalist nonsense.

It's racial fan-fiction written by an American Brat, who cannot hide the fact he thinks Korean people are all inferior dullards.

Since this is not a Marxist-Leninist state committed to the improvement ofmaterial living standards, but rather a nationalist one in which the leader’s main function is to embody Korean virtues—which are not seen to include intellectual brilliance anyway—the relative inferiority of Kim Jong Il’s genius troubles propagandists less than an outsider might assume. It is in no small part because he appears more human and vulnerable than Kim Il Sung, and thus a more convincing embodiment of the child race itself, that the Dear Leader is so dear to his people, even if he is not as fervently venerated as his father.