A survey this week claimed that Protestant and Catholic teenagers can identify each other by the brand of trainers they wear, the shopping bags they carry... even the night of the week they visit the cinema. Here, three Belfast Telegraph writers recall their introduction to 'the other side' and ask what, if anything, has changed since.
The first school I went to was an Orange hall. I suppose some might assume there would be potential there for early indoctrination, but actually I think at that age we were all too consumed with ourselves in our small world to wonder, or worry about, others of a different faith.
I certainly can't remember us relying on identification pointers like what supermarket carrier bag was likely to be in the hands of which side of the community on what particular evening. (Where does this stuff come from?)
South Derry, where I grew up, was like much of Northern Ireland still; a swathe of small townlands, villages and larger towns which could be designated predominantly Catholic, or predominantly Protestant. In many cases, very, very predominantly indeed.
In the dark days of the Troubles, there wasn't much genuinely mixed territory. Some places back then could safely be described as 100% mono-religious.
The small village I grew up in was around 98% Protestant. The Orange hall came in to play to cater for the overspill from the main primary school. Our school dinners (always cold by the time we got them) were bussed in.
I don't remember much debate about difference between ourselves and our Catholic peers, but I do remember division in telecommunications.
In the wider area, there was a Catholic phone-box (left) and a Protestant phone-box - so designated because of the religious make-up of their respective hinterlands.
I went to a mixed secondary school - the Rainey Endowed in Magherafelt.
The Rainey was, and is, an amazing place - although it would be fair to say I didn't fully appreciate that as a child.
To me, the main divide between myself and some of the other pupils (and even then it wasn't something I dwelt on too much) was not a religious one, but a class one.
Some pupils - Catholic as well as Protestant - came from well-off backgrounds. I was from the council house contingent - again, both religions were well represented there.
I do remember feeling jealous of my Catholic classmates when they got excused from, say, maths for Mass. But I did have some sympathy for them re RE.
The softie home economics teacher who took us (girls) for what was nominally religious education often segued off into talk about food preparation. The Catholic (boys), however, had for RE a maths teacher so fierce I used to tremble if I passed him in a corridor.
Out in the outside world, the school bus home could be described as predominantly Catholic. The local convent grammar back then catered for girls only.
I pitied them for their strictly enforced uniform of long pinafores. Our skirt length was regularly monitored, too (by mothers as well as teachers), but we seemed to have more licence shortening it with the old roll-it-up-at-the-waistband trick.
I envied the Catholic girls, though, what I felt was their greater self-confidence. To me, the convent girls always seemed more self-assured. Even in their frumpier skirt length.
When they were introduced, they shook your hand. Beside them, red-haired, freckly me, I was the gauche, self-conscious mumbler.
Maybe back then, the convent school taught life skills. Our school was more focused on how you handled algebra than how you handled social interaction.
I doubt any of us - Catholic and Protestant alike - was so sophisticated we could identify the other religion by supermarket carrier bags back then.
But there were, of course, those other familiar pointers we still note. First names. The way you say the letter 'h' ...
We may shake our heads at the bags. Sadly, we all still carry that baggage.
By Malachi O'Doherty: When I was a lad, spotting the difference between Protestants and Catholics was as easy as telling Stork from butter. Quite simply, in our neighbourhood the Protestant children all had fathers in the police.
They were cleaner than us. My own mother, wiping my mouth with a flannel before sending me out to school, or Mass, would often say, "There now, that's a bit more Protestant-looking".
Our Protestant neighbours lived different lives. They went to different schools, where they studied different subjects, and, on Sundays, if they went to church at all, they went in a different direction.
And since school and the Church were central to our lives, Protestants were always outsiders. Though you would find yourself playing with them in the evenings and through the long summers, you never saw them in the queue for confessions on a Saturday morning.
As I got older, I learnt that Protestant girls were much easier. We all had Catholic hang-ups and they didn't, so it stood to reason that they would go further and faster than the girls we met through the Legion of Mary.
My own initial experience confirmed this, though I hadn't tested a sufficient number to constitute a statistically reliable sample - but not for the want of trying.
At the basis of this prejudice was a view that Catholics were much more religious than Protestants. We all went to Mass every week. We went to Sunday devotions, benediction, sodalities and missions and ceili dances in parish halls.
One of the early surprises on deeper acquaintance with Protestants was that some of them were more hung up on religion than most of us were.
We seemed to integrate religious practice into chasing girls, hanging out with other boys and telling dirty jokes. There was an unvoiced understanding that you weren't supposed to take it too seriously.
I achieved that insight when I went through a year in my mid-teens of wanting to be a priest and had the whole notion scoffed out of me.
I have often found that many Protestants have little understanding of this side of Catholicism; that people who go to Mass every week might be offended if you described them as religious.
I still encounter the assumption that a church-going Catholic is being manipulated by the priests, when the poor priests are actually being run ragged by the demands of the people.
One of the most common prejudices about Protestants pays them a compliment. It says that they are straight-dealing people, never short-change you, always keep a promise and are a bit more careful with their money than is proper.
By contrast, the Catholic always buys his round, is lavish with his cash and never worries too much about you paying back what you owe. I have yet to meet this Catholic.
This stereotype played through the peace process, where it was said that Protestants - being people of the Book - took political promises literally, whereas Catholics could parse the nuance out of the context.
In fact, it was Catholic Sinn Feiners who insisted on the letter of the Good Friday Agreement, while Protestant unionists wanted the spirit of it, on the decommissioning deadlock.
So, all of these stock labels we have for each other are useless - unless you've never actually met a Catholic who'll give you the right change, or a Protestant who can whistle a tune.
I used to think that Catholics were more bawdy, more cheerful, more relaxed and more fond of a drink until, one Eleventh night, in the line of duty, I found myself in the Rangers Supporters' Club in Sandy Row.
Our eyes aren't closer together; we are not more liberal, or more slovenly, more devout, more poetic, or musical, more witty, or even more Irish.
And yet people still believe some, or all, of these myths and they are being passed on to our children. Pathetic.
By Suzanne Breen: As a child growing up in an area of south Belfast unscathed by the conflict, I harboured no sectarian stereotypes about the "other side". Indeed, until the age of 11, I was blissfully unaware that Northern Ireland was divided into "us" and "them".
That all came crashing down on my second day at a predominantly Protestant secondary school. "Are you a Protestant or a Catholic?" one boy asked me in front of a crowd of other pupils.
"I think I'm a Catholic," I replied in my childish naivety. And so began five years of unremitting sectarian abuse. "Mother Teresa" I was christened.
It was only the boys who were sectarian. I remember one girl advising me to shout something back in retaliation at the ring-leader. "Call him an Orange b******," she suggested. I didn't even know what that meant.
It was presumed that, because I was one of "them", I supported the IRA. I couldn't have told you a single thing about the IRA back then.
But I remember, in 1981, every morning after a hunger striker died, my classmates rising to their feet, banging their desks and jeering at me.
I grew up in a household which wasn't even nationalist, let alone republican. My mother voted Alliance. She thought the SDLP were extremists.
Over 20 years into the peace process, it's depressing to learn that young people are still trying to establish each other's religion by the most bizarre means. Carrying a Tesco bag, or going to the cinema on a certain day, apparently identifies which foot you kick with.
I don't know what made that boy at school guess I was a Catholic all those years ago. My name was neutral. Maybe he was suspicious of my black hair and pale skin.
In those days, the religious detectives didn't seek clues in shopping bags, or movie nights, it was all about "the look" and whether you said "aitch", or "haitch".
Many people don't meet anyone of the other religion until they go to university, or enter the workplace.
Growing up in a unionist area, the opposite was true for me.
Except I didn't see those around me as Protestants. They were just neighbours and friends. I knew they went to other churches on a Sunday. But I didn't realise this was significant and categorised them as belonging to one tribe and I to another.
Catholics can portray Protestants as a dour, rigid people. Some fitted the bill - like those who chastised my mother for hanging out her washing on a Sunday. But I knew far more who defied that sweeping stereotype.
My mother's best friend was Julie Leckie, a retired professional ballroom dancer, who had travelled the world. She brought more joy and light into my childhood than anybody I knew.
My family shopped in Sandy Row every week. I never set foot on the Falls Road until I decided as a teenager. Until then, I was far more exposed to unionist culture.
I remember, as a six-year-old, watching the Twelfth parade and being intoxicated with the bands and the sheer spectacle of it all. I begged to be brought back again, but even my Alliance-voting mother refused, telling me I'd understand why when I was older.
As a teenager, I was taken to Protestant churches by my mother on her own personal cross-community mission. I remember attending Fitzroy Presbyterian and All Saints'.
They held no allure for me compared to the mystery and magic of Catholicism, although soon I would no longer believe in it.
It's wrong to see bigotry as just confined to the working classes. The school I went to was solidly middle-class.
These kids didn't come from areas where loyalist paramilitaries glared down from gable walls. And the sole teacher who challenged them was a working-class Protestant from the Belvoir Estate.
Years later, I found out that I wasn't the only Catholic in my class; that there was one boy who pretended to be a Protestant. What a sad indictment of a sick society.
Yet it also brings a smile to my face. He had red hair and freckles. How on earth did he manage to get away with it?