This coming-of-age ritual – you might call it a Wasp Bar Mitzvah, although there are now, six generations on, Jewish Rockefellers, too – is part of a broader tribal culture that has allowed the Rockefellers, more than 70 years after their founding patriarch's death, to remain a powerful force in US civil society.

“There's no family like the Rockefellers in American life,” says Richard Holbrooke, former US ambassador to the United Nations and chairman of the Asia Society, which was founded by a Rockefeller. “They have a very developed sense of reticence and responsibility. What's amazing is how many institutions they have touched through their multiple efforts.”

As America's new gilded age starts to sputter, the Rockefeller family is the most influential ?living extension of its first gilded age: the raw, revolutionary decades after the civil war that laid the foundations of modern US capitalism. The family's forefather, oil mogul John D. Rockefeller, is described in Titan, Ron Chernow's biography, as “an amalgam of godliness and greed”, who was both the nation's “fiercest robber baron” and its “foremost philanthropist”. Standard Oil, the mighty trust he created was broken up by a Supreme Court ruling in 1911. But by then, Rockefeller was already devoting most of his time to giving his money away.