IF Boris Johnson’s premiership is as short-lived as the bookies predict, one abiding memory will not be forgotten by the British public.

‘Not even his own brother trusted him’.

Jo Johnson’s shock resignation as an MP and minister stunned those in the political bubble, providing cheap and easy hits for the Prime Minister’s opponents.

But the impact was felt far beyond Westminster, becoming the Heineken of political stories – reaching the parts other political stories cannot reach.

There is a fascination with family feuds in British politics, particularly when the rivalry is between brothers.

David Miliband v Ed Miliband. Jeremy Corbyn v Piers Corbyn.

And not just in our politics, either, with Liam and Noel Gallagher’s barbs between each other providing tabloid copy for decades.

Power struggles between siblings have been a theme in literature for centuries, from the Bible to Shakespeare, from Sherlock Holmes to Game of Thrones.

The greatest moments of villainy, humour and love in the entire Marvel cinematic universe are when Thor and Loki are together on screen.

"Loki is beyond reason, but he is of Asgard and he is my brother” Thor tells Black Widow in defence of his sibling, only to be told he had killed 80 people in two days. “He's adopted,” Thor adds.

When it comes to politics, we seem to place a higher expectation on family members to agree with each other. All Kennedys must be Democrats. All Ewings must be Scottish Nationalists.

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And, therefore, all Johnsons must be hardline Tory Brexiters.

It’s a lazy assumption I made myself when I got to know Boris’s half-brother Max in Australia.

Max wasn’t a diehard Brexiter – in fact, he remains fairly ambivalent about Brexit, recently telling an interviewer "the best thing … is a quick decision for Brexit to either happen or not happen".

His dad Stanley voted Remain in the 2016 referendum. Jo openly supports a people’s vote on Brexit.

Another sibling, Rachel, fiercely opposes Brexit and stood for the Change UK Party in the recent European elections.

She said last week that Boris is "outnumbered" in the family when it comes to the UK’s departure from the EU, and that around the dinner table they can no longer discuss Brexit.

Like countless families across the UK, they disagree on politics to varying degrees.

That shouldn’t shock us, or be used as a political football.

Given that Jo Johnson emotionally spoke of the "unresolvable tension" between his family loyalty and the national interest, the delight among political opponents was perhaps misplaced.

If we want our politicians to reflect society, we shouldn’t assume that their family members automatically agree with them, and we should be wary of publicly chastising them when they don’t.

In the fallout from Jo Johnson’s resignation, I was reminded that party activists campaigning for votes at election time often knock on the door of a house displaying the poster of a rival party.

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Just because one family member is voting one way doesn’t mean they all are.

One party campaigner told me how they knocked on a door during a recent election campaign in Scotland and chatted to a woman who was voting Labour. From elsewhere in the house, a man shouted that he was voting UKIP.

“Don’t worry, I’ve hidden his polling card,” the woman whispered to the activist.

Political differences in ordinary families exist and are accepted, so why should we expect the Johnsons to be any different?

I believe those who engage with people they disagree with will learn more than those like Labour MP Laura Pidcock who refuses to be friends with her political opponents.

I prefer her colleague Jess Phillips’ outlook. “I have learned that life is more interesting if I befriend different sorts of people, and then do as I do with all the people I truly love – row a lot and spend a lifetime taking the p*** out of them,” she once said.

Or Kezia Dugdale’s remark that she and her SNP partner Jenny Gilruth know how to "disagree well".

But while different political party preferences have existed within families for decades and will continue to do so, the binary constitutional debates of recent years have added a sharper edge to disputes.

Some relationships have been torn apart by Remain/Leave and Yes/No.

In the run-up to the independence referendum there were families where all political talk was banned at the dinner table or in the pub to avoid blazing rows and tears.

In the EU referendum campaign, young children frequently fell out with older relatives voting Leave.

It was reported that a woman was so furious with her uncle for voting Leave that she planned not to invite him to her wedding.

Divisions have become more entrenched, with people defined by how they voted in these contests.

It has led some to question if binary constitutional referenda are good for society. Ahead of his return to the stand-up comedy circuit, Ben Elton last week lambasted them, arguing that ‘Yes/No questions in politics’ are just too simplistic.

If we are to have any more of these contests – and I do believe a confirmatory vote on Brexit is still the best way to resolve this crisis – everyone needs to work harder to address the toxic atmosphere they can create.

The Referendums Bill going through the Scottish Parliament to pave the way for another independence referendum makes no mention of the deeper divisions it could cause or the risk of intimidation and harassment – something that should be addressed by MSPs.

Yesterday, it was revealed that a group of business executives, faith leaders and charities have met to discuss a new grassroots campaign to help bring people back together across the UK.

Jo Cox’s family is said to be playing a key role, along with the Archbishop of Canterbury.

I have had the privilege of meeting her sister, Kim Leadbeater, on two occasions and her enthusiasm to fix our divided society is contagious.

Before the EU referendum, Labour MP Jo’s life was tragically cut short.

Her words that "we have far more in common than that which divides us" are vitally important today as the Brexit endgame nears.

In these difficult times, political disagreements are necessary and unavoidable, even within families. But we must never lose sight of what we have in common with each other.