Nigeria, March 9 -- In 1979, Iran rose in fury against a king.

Millions poured into the streets to bring down the rule of Mohammad Reza Pahlavi, the monarch whose dynasty had ruled the country with imperial certainty. The revolution that followed promised something radically different. It promised that power in Iran would never again travel through bloodlines. No sons inheriting thrones. No families sitting atop the state as if it were private property.

The Islamic Republic was supposed to end all of that.

Nearly half a century later, history has taken an unexpected turn.

Following the death of Iran's long-time supreme leader Ali Khamenei, the clerical body tasked with selecting his successor chose a man who had spent most of his lif...