Hereditary rule wasn't exactly on the agenda at the framing of the Constitution. But If Hillary Clinton wins the presidency, two families will have ruled America for 24 of the last 32 years. (This would have been guaranteed if Jeb Bush had prevailed in his primary.)
Then again, politics have always been a family affair in the US: half the first Congress served alongside a close relative. From the 19th-century Adams to the Udalls, Bushes, Murkowskis, Kennedys, and even the ascendant identical Castro twins, the tendency continues for Americans to elect families, perhaps because their names act as brands to orient voters through our thicket of elections.