If in doubt, we used to talk about the weather. Or if not that, then why the trains were late again, or how sweet someone’s baby was: the kind of routine bland nothings you exchange with strangers on the street. But something about the way we speak in public is changing.

A few days ago I was in Aldi, making the usual small talk at the checkout. When the cashier said she was exhausted from working extra shifts to make some money for Christmas, the man behind me chipped in that it would be worse once “she takes all our money” (in case Rachel Reeves was wondering, her budget pitch-rolling is definitely cutting through). Routine enough, if he hadn’t gone on to add that she and the rest of the government needed taking out, and that there were plenty of ex-military men around who should know what to do, before continuing in more graphic fashion until the queue fell quiet and feet began shuffling. But the strangest thing was that he said it all quite calmly, as if political assassination was just another acceptable subject for casual conversation with strangers, such as football or how long the roadworks have gone on. It wasn’t until later that it clicked: this was a Facebook conversation come to life. He was saying out loud, and in public, the kind of thing people say casually all the time on the internet, apparently without recognising that in the real world it’s still shocking – at least for now.

I thought about him when the health secretary, Wes Streeting, voiced alarm this week that it was becoming “socially acceptable to be racist” again, with ethnic minority NHS staff fighting a demoralising tide of things people now apparently feel emboldened to say to them. What Streeting was describing – not just unabashed racism, but a sense of inhibitions disappearing out of the window more generally – goes well beyond hospital waiting rooms. You can feel it at bus stops, where polite inquiries about why the 44 doesn’t stop here any more end up wheeling off at sudden wild tangents about chemtrails or the government spying on you; or in casual school-gate chats, where otherwise perfectly ordinary-seeming parents turn out to have some very odd ideas about vaccines.

A friend calls it “sauna politics”, after the surreally conspiracy-laden conversations she overhears in her local leisure centre sauna. But whatever you want to call it, it’s as if people are suddenly voicing their interior monologues – things that until recently they’d have been embarrassed to say in public, or sometimes even to admit to themselves that they thought – out loud. After all, they can say this stuff online and nobody bats an eyelid. Why not in a hospital waiting room? It’s the conversational equivalent of young men trying out things they’ve seen in online porn on real-life girlfriends and being surprised when it goes badly – except this time the main culprits are less likely to be confused teenagers than their parents, unmoored by the dizzyingly fast collapse of social norms online and the return of slurs they haven’t heard voiced out loud since childhood.

Middle-aged radicalisation sounds almost like a contradiction in terms, a reaction to all the stereotypes about settling comfortably into your rut. Besides, in our own heads, if nowhere else, gen X were always the mild-mannered peacekeepers of the culture wars: not old enough to be deemed reactionary or young enough to be woke, and instead occupying a kind of cheerfully moderate Goldilocks zone in-between. But something seems to have happened to us as we hit the midlife crisis years. Gen Xers are now old enough to start worrying that the world is changing and leaving us behind: that if we get made redundant we might not get hired again, that our marriages may not survive the shock of the kids leaving home, that our views are out of date and someone is out to get us for them, that people are laughing at us behind our backs. Though most of us get through it without a political meltdown, this time of life certainly has its casualties, seeking an outlet for bottled-up rage and disappointment that life hasn’t turned out as planned.

It’s gen Xers, not grumpy pensioners or teenage boys beguiled by rightwing influencers, who are powering the populist insurgency now. Only 19% of British fiftysomethings voted Reform UK at the last general election but a third of those aged between 50 and 64 would do so now, according to YouGov, which is a staggeringly fast turnaround for the “Cool Britannia” generation that put Tony Blair in Downing Street – and key to the party’s move from fringe to mainstream. In the US, gen Xers have been dubbed the “Trumpiest generation”, because they’re more likely than any other to identify as Republican.

Yet with rare exceptions such as the Smidge project – a three-year ongoing international study of how conspiracy theories and disinformation spread among 45- to 65-year-olds, and how deradicalisation could work for this age group – we show amazingly little curiosity about how middle-aged minds have been shaped by living through the great unregulated free-speech experiment.

My generation likes to think we’re above being influenced by what we see online: that we’re more tech-savvy than our parents, less TikTok-addled than our kids, and mature enough to separate it all from real life. But the evidence suggests we’re not nearly as capable of compartmentalising as we think. Perhaps the only surprise, given how thin the fourth wall separating online and offline discourse always was, is that it’s taken this long to break.