The Marching Morons?
Certainly the premise of Idiocracy is drawn from Kornbluth's dystopian short story. Lacking, of course, is the hyper-intelligent elite minority enslaved by the inertial mass of the idiot majority, & the protagonist's ruthless solution.
Of course both Mike Judge & CM Kornbluth draw from inaccurate assumptions—stupid people, as opposed to those who are truly developmentally disabled, can have perfectly intelligent children. Stupidity is more of a lifestyle choice than genetic predisposition.