The first response of any politician to a media attack on his or her family is to erupt in understandable fury and demand a retraction or a right of reply. Cooler, second thoughts usually lead to the conclusion it is best to ignore it for fear of making matters worse.
Equally, the first response of any newspaper facing a politician's demands for a retraction or right of reply is to refuse, citing freedom of the press and fair comment. There are seldom any second thoughts.
So it is surprising that Ed Miliband's anger over a Daily Mail feature attacking his dead father, the Marxist historian Ralph, has led to him insisting on a right to reply in the same newspaper. But it is even more surprising that the paper has agreed.
Perhaps it is part of the post-Leveson effect, which has seen newspapers becoming more cautious than in the past, for good or ill. Or maybe the Mail believes, in defending his dad, Miliband will prove their point that he is a rabid socialist. And Miliband must be aware of the dangers of that, and of being drawn into some sort of pointless debate with the newspaper.
But, whatever the motivations, it is a highly unusual development.
The piece in question, by writer Geoffrey Levy, was largely just a well crafted re-hash of Miliband senior's background and political views. The fact he was a Jewish immigrant, a Marxist and was sceptical of the notion that socialism could ever be achieved by Labour or maybe even through parliamentary means is not just well known, it is what drove him all his adult life and made him famous through his writings and teachings.
No secrets there then, and a political analysis still held by large numbers of people to this day. So what upset Miliband so much, or is he being a bit too brittle?
First, the piece sat under the online headline: "The man who hated Britain: Red Ed's pledge to bring back socialism is a homage to his Marxist father. So what did Miliband Snr really believe in? The answer should disturb everyone who loves this country."
Along with the headline, the core passage in the piece is the quotes from the 17-year-old Ralph Miliband's diary stating: "The Englishman is a rabid nationalist. They are perhaps the most nationalist people in the world...you sometimes want them almost to lose [the war] to show them how things are. They have the greatest contempt for the Continent... To lose their empire would be the worst possible humiliation."
So it was the English not the British, it was "almost" lose the war, and the English didn't like Europe or the loss of empire (imagine). And all from the considered pen of a 17-year-old - and that should be a lesson to the Facebook and Twitter generation.
But it is the fact Ralph Miliband was a Marxist that is the real "threat" perceived by the Mail, the newspaper whose brief support for fascism and Oswald Mosley's Blackshirts in the 1930s (defeated at the Battle of Cable Street by anti-fascists inspired by the Spanish Civil War slogan 'they shall not pass/"No Pasarán") is equally well known and just as much a matter of fair comment as Miliband Snr's pronouncements.
But the descendant of that paper cannot be automatically assumed to hold the same views, as if it was in its bloodstream.
That "threat" from Miliband Snr came from the fact he was unapologetic about his desire to transform Britain into a socialist state. The implication being that anyone who wants radical change in the UK is actually attacking the very essence of Britishness, maybe even being unpatriotic, although Miliband served in the Royal Navy in the Second World War.
It is the conflating of these strands into an apparent attempt to demonise his father that seems to have infuriated Miliband, rather than any attempt to suggest he is out to realise his father's dream, or that Marxism is somehow passed down the generations through the DNA, both of which are equally ludicrous.
So he is unlikely to want to get into a fight over his father's political beliefs, but instead to focus on what he believes is a character assassination aimed at hurting him. But he must have another objective.
The 2015 election campaign is stacking up to be one of the toughest and most bitterly fought for two decades. And if there are echoes of the anti-Kinnock campaign of 1992, as expected, it will get personal, just see George Osborne's assault on "Marxist" Ed at the Tory conference, which was clearly a reference to the Mail attack.
So Miliband wants to put down a marker - you can attack me and you can attack my policies but hands off my family or their loyalty to Britain. Well, it's worth a shot.