My six-year-old son announced, from the back of the car, that he was backing Boris Johnson. My wife, who’s voting Lib Dem, was horrified, accusing me of indoctrinating the boy; I resisted the temptation to film a video and post it on Twitter, to be retweeted by Tories and hate-tweeted by others accusing me of brain-washing, even child abuse. But when we questioned our son it soon emerged that he had heard — whether from a news report, or from his parents talking — that Boris Johnson was in favour of cake and in favour of eating it, and this was very much a policy he could get behind.

It’s easy to assume that any political opinion expressed by a child must be the result of indoctrination, but it’s not true. While all political scientists know the best way to predict someone’s voting preference is to look at his or her parents’ voting preferences — or, if there is disagreement, at the mother’s voting preference — the mechanism behind it is unclear. There may be a genetic element — studies have suggested that identical twins are more similar in their political attitudes than non-identical twins — or a desire to fit in with one’s parents’ beliefs. This does not in itself imply indoctrination; a survey in America demonstrated that young people’s politics are more strongly correlated with what they think their parents’ politics are than with what they actually are, and this is no more sinister than a child adopting a parent’s football team.

In fact, direct indoctrination is counter–productive: young people from highly politicised households, in both America and here, are statistically more likely to deviate from their parents’ political preferences than those from less politicised households. What seems to happen is that children adopt their parents’ views to begin with, are then exposed to the opposite viewpoint at university — coming from politicised backgrounds, they are more likely to start conversations about politics — and reject the callow beliefs they have inherited. The idea that universities are hotbeds of left-wing indoctrination is overdone — they are often places where previous indoctrination is undone.

A friend of mine who lectures on politics had a student who began this year’s course as a Labour tribalist and ended it, having been exposed to other arguments for the first time, as a Hayekian free-market libertarian who thought feminism was a conspiracy theory to hold back business. (Nothing to do with my friend, who voted for Corbyn in the 2015 Labour leadership election.)

And yet children ask questions, particularly in general elections: who are these people on the television? Why are those people giving us balloons? Are they clowns?  Usually if a child asks questions you don’t want to answer, you can refer them to a book — like most people my age, I learnt the facts of life from the Usborne book How Your Body Works, and for a long time thought that sex was pretty much identical to steam trains coupling — but most children’s books about politics avoid parliamentary politics altogether. They will tell you that there are 650 MPs, for example, but not that the Labour party and the Conservative party have different opinions.

It’s not impossible to talk to children about politics without leading them in one direction — the children’s theatre show How Does This Politics Thing Work Then? manages to do so very well without any bias that I noticed, but with lots of jokes about bottoms that our son enjoyed — but it is hard.  For my wife and me, it was the first time that our son was asking questions where we had not agreed on the answers beforehand (we have always presented a united front on the divisive eating-cake issue) and to begin with we avoided answering altogether. Who wants children’s tea to turn into Question Time?

Dr Amanda Gummer, child psychotherapist and founder of Fundamentally Children, argues that this is a mistake. ‘The more children understand about how the world works, the more engaged they are with it, and the more positive they feel about their community, society and country,’ she says. ‘That’s really important to create socially engaged adults. If they’re old enough to ask the question, they’re old enough to deserve an answer.’ And actually the fact that my wife and I disagree about politics may be a bonus: ‘For older children, it’s important to understand that not everyone agrees about everything. You can dis-agree with someone and still love them: that’s a very important lesson for a child to learn.’

Talking to children about politics can thereby inoculate them from the two main problems in our democracy — political apathy on the one hand, and hyper-partisanship on the other. It is tempting to explain politics in terms of Goodies and Baddies, but that’s what Twitter’s for. I’ve gone back to basics, and Burkean political philosophy: ‘You know how sometimes people have an idea that they think is really good, but turns out to be rubbish?’ ‘Like when Wyatt thought he could do a cartwheel?’ If you knew my son’s friend Wyatt you’d see what a brilliant metaphor this is for Corbyn’s socialist Utopia, but I don’t want to race ahead too far.

I tell our son what I think, and my wife tells him, respectfully, rationally and clearly, that I’m talking nonsense, that sharing is caring, and that Tories only share cake with people who already have too much cake. Also, the Liberal Democrat canvassers included a dog. We live in an ultra-marginal constituency, and we shall be cancelling each other’s votes out for years. Some time after 2031 our son could swing it one way or the other.