Between them they have covered almost every major public event that has shaped our lives in the past half-century. They have been the chosen conduits for politicians and princes to reveal their personal thoughts to television audiences of millions. And now a third generation of Dimblebys is continuing the family tradition.
The last general election was an apt showcase for the power and influence of the old firm of Dimbleby & Dimbleby. The most media-conscious of contests, where soundbites took precedence over substance, ended with David and Jonathan fighting it out as the respective anchors of BBC and ITV.
The common perception is that the journalistic lineage of the Dimblebys started with Richard, the father of David and Jonathan, who became the BBC's Voice of the Nation. In fact, it stretches back to Jabez Bunting Dimbleby, born to a staunch Methodist family in Hull in 1827, who became a reporter and moved to London. His son, Fred, was proprietor of the Richmond and Twickenham Times by 1896 - a paper of which David Dimbleby later became chairman.
Richard began working for BBC radio news in l936, where he was the first broadcast journalist to report from the scene of the story; he started outside broadcasts and vox pops. In time he was the reassuring voice at the great ceremonies of state. One of his most enjoyable tasks, he said, was to present Panorama, the first forum for serious documentary and debate on television.
David joined the BBC in l960, rising within the corporation from one prestigious job to another, on to Panorama, Question Time and state occasions. Thanks to his newspaper interests, he is now a millionaire.
Jonathan was a later entrant, first joining BBC Bristol, then Thames TV, TV-am, and then back to the BBC. He hosted On the Record for five years, and has hosted Any Questions since l987. He hit the headlines with his documentary The Prince of Wales: An Intimate Portrait, in which the Prince admitted adultery. Thanks to the serialisation rights, he too is a millionaire.
The Dimbleby brothers' partners are also in the media. Jonathan married the journalist and author Bel Mooney, with whom he has two children. David's marriage to the cookery writer Josceline Dimbleby broke up acrimoniously, with Mrs Dimbleby striking out at her husband in the tabloids. The couple have four children. David's new partner is the television producer Belinda Sykes.
One of David's daughters, 20-year-old Kate, is about to launch her television career on a Carlton cabaret show, The Warehouse. "Nothing", she says, "could be more terrifying than finding yourself profiled by one of the Dimbleby brothers."
Daniel, 23, and Kitty, 17, son and daughter of Jonathan and Bel, are also starting out in the media. Daniel is a researcher for an independent television company, Bazal Productions, while Kitty has been writing pieces on the environment. Over the past three years she has had articles published in the Daily Mail, where she is about to begin a work-experience placement.
Daniel has already been the subject of journalistic investigation. He recently cancelled his wedding to Clare Simmonds, daughter of the cartoonist Posy Simmonds, leaving her, according to a newspaper report, "red-eyed ... shocked ... devastated". The newspaper in question? The Daily Mail. Ms Mooney said: "It was upsetting for Kitty, especially as she is meant to be working there. I had to tell her other papers may have done it in a much worse way. It's one of those lessons one has to learn".