Have you ever met a Protestant with a sense of humour? Or one who could hold a tune. Or even write a poem? I ask because there has long been doubt about this.
A friend's father approached me after a social occasion one day and asked if any research had been done into the question of whether Protestants dig with a different foot. I wasn't aware of any. My friend's father is still waiting for confirmation of the received wisdom of ... well ... of whom?
The assumption that there are significant differences between Protestants and Catholics remains powerful and yet superficial.
The cliche broke surface in the Fodor travel guide in an item about Belfast murals. Those in Catholic areas, it said, "often aspire to the heights of Sistine Chapel-lite".
This is a pretty daft comment. It carries more than the suggestion that the Catholic communities throw up better artists, but also that their religion sets a standard for them.
Anyone who thinks like that doesn't really know Catholic Belfast and how little it concerns itself with religious art these days.
True, a lot of homes would still have a picture of the Sacred Heart in the living room, or of Our Lady of Perpetual Succour.
And some of the murals used to have religious themes. Back at the time of the hunger strikes, there was a mural in Beechmount which showed a blanket protester in his cell with the Virgin Mary standing beside him in the posture of the Mediatrix of all Graces, showering God's love upon the world. But there hasn't been a lot of that since.
Loyalist murals "resemble war comics without the humour", according to Fodor. This is true of some of them, as it is true of many of the republican ones.
And yet, some of the Shankill murals are much more sophisticated - and deftly executed, too.
Did the writer of this article not see Ross Wilson's William of Orange mural in Sandy Row? It's only a short walk from the bus station.
But what is offensive about these comments is not that they dismiss, or disparage, fine murals. It is that they repeat an old trope that Protestants are dull-witted, while Catholics are vibrant and imaginative. And nothing supports this idea, though it has been with us a long time.
It's hard to prove the point without head-counting among our visual artists, poets, novelists and songsters, but that would feel like a grubby thing to do.
In many - perhaps most - the least interesting thing about them is how they identify in terms of the sectarian faction they might be perceived to have been born into.
Some sectarianism in Northern Ireland is very lightly passed on. I got a Press release recently about a photographic exhibition in Belfast presenting the work of Toby Binder. His latest book is called Wee Muckers - Youth of Belfast.
That's appalling. Who are these "wee muckers"?
How many young people in Belfast would think of themselves as "muckers"? Any of them?
But the idea that all people of a community are the same is perpetuated further in the Press release, which describes the peace walls as dividing "homogeneous communities".
Yes, most people in the Shankill area are of Protestant extraction and have unionist convictions and most people from the Falls were baptised Catholic and vote - if they vote - for nationalist parties.
But the term "homogeneous communities" assumes a whole range of commonalities between neighbours and misses the obvious; that within families, let alone streets, or whole neighbourhoods, there is huge divergence of attitude, aptitude and opinion.
And to be living in a time in which you have to tell people something so banal.
What Binder had in common with Fodor is that both are external eyes looking in at us and treating us as if we are coherent tribes at odds with each other and not part of the modern world at all.
I have been writing a bit about this for my next book, Fifty Years On, which comes out in August.
One of the shocks was reading some of the journalism around the early Troubles and seeing this description of us as tribal and unified in our sectarian blocs and this being written about as if it was charming and rare. This is just another way of patronising the quaint Irish.
There are, of course, differing cultural trends between our communities, as there are opposing political aspirations.
Councillor John Kyle speaks in my book of the sense among his peers at school that there was no point in doing A-Level English when you had the chance to work towards a career in the sciences and earn more.
And he says that the early unionist leaders were outflanked by the eloquence of the nationalists of the time.
But there is no distinctive oratorical brilliance in either tradition now.
The flourish back then was a fluke. If it was evidence of native Catholic brilliance, the same Catholic advantage would still be with us.
The best speaker among our politicians now is Naomi Long, who was a Protestant with a scientific training.
The Northern Ireland Life and Times Survey has been teasing out differences between Protestant and Catholic attitudes for decades now and finds out things like fewer Protestants than Catholics accepting that someone in their family is gay, or feeling European. But these are never overall descriptors of a community attitude.
The tendencies revealed by the Life and Times Surveys suggest that Catholics want to be thought generous, while Protestants are more concerned to be thought fair. But these are tendencies within these communities, not defining attributes.
Protestants were found to be more likely to believe that migrants come here specifically to access welfare benefits. One might ask if attitudes are inherent, perhaps derived from the receding religious culture, or whether they are just cultivated in communities as marks of distinction from each other, in the way that they divide up the Israel/Palestine question between themselves.
Whichever it is, the differences aren't of sufficient scale to help identify anyone. You can't tell if someone is a Catholic by asking if there are gays in the family, or if Israel is doing a good job of defending itself.
You can stare all day at the murals in Ballymurphy, or the Falls Road, for evidence of the influence, or guiding spirit, of Michaelangelo and you'll find that he, too, used brushes and liked colour and the human form.
You'll find exactly the same in murals on the Shankill.
Claiming that Catholics are more creative than Protestants is just sectarian.
Fifty Years On: The Troubles And The Struggle for Change in Northern Ireland by Malachi O'Doherty will be published in August by Atlantic Books, priced £18.99