People here talk about "mixed" marriages, "mixed" districts and streets, and outsiders marvel at such magnification of irrelevant difference. How can people who look like each other, interbred for centuries, expect anyone else to respect their quarrels?
But some know well how it sounds elsewhere to be so aware of others' origins, that people of different Christian denominations happen to be partners, to have married each other, or live next door to each other. Even the terms are exaggerated: "origins", "background", "tradition".
Certainly, some only feel safe "among their own". Many consider segregation and separation facts of life, about which nothing can be done. Many never wanted to be separate, and think that more integration should surely be possible now. The ebb of violence has made for more self-awareness and at least the desire for more individualistic choices.
The Housing Executive, which is responsible for allocating public housing, has a list of more than 600 families who wish to live in an estate that is neither all-Catholic nor all-Protestant, but mixed in healthy proportions.
Public housing is the only option for those who cannot afford mixed middle-class districts, though all but around 3 per cent of it is dominated by one community or the other. Housing policy can not turn on a sixpence: policy-makers plan a modest initiative.
A week ago, the Housing Executive said that in September about 20 families should be able to move into a small "mixed" development in Enniskillen. It will include several immigrant families as well as the North's common or garden Protestant/Catholic couples, the score of them to sign a Good Neighbour Agreement that commits them to work on building community spirit and forswear flag-flying and graffiti-writing. A second mini-mix will start in the next two years in Loughbrickland, Co Armagh.
The towns have their lakes in common, though Loughbrickland's is tiny compared to Upper and Lower Lough Erne.
For the Housing Executive's purposes, the most important thing the towns share is a low level of local tension, and thriving integrated schools. Both also have numbers of new immigrants.
The majority of the 600 families who would like mixed estates live, like the bulk of Northerners, in Belfast. Offer them Enniskillen, 70 miles away, or even Loughbrickland, half an hour down the road to Newry, and most would say no thanks. But modern Belfast, with the greatest need for public or "social" housing, is no place for experiments.
They were tried before, back in the edgy 1960s before the Troubles-proper erupted. People were decanted together out of Victorian slums, Catholic and Protestant, into the airy uplands of Springmartin, Moyard, New Barnsley, and the spacious suburbs of Rathcoole. None of those names suggests pleasant places now. But some 40-year-olds remember bright new houses from their childhood, the hills or Belfast Lough in the background, and a dim awareness that there were neighbours in the RUC or "of the other religion".
In the first years of the Troubles, in some places over a few days of mayhem, the fragile mix got shaken out into its original components. A woman now in her late 60s looks back regretfully to her house in Lenadoon, where she and her new husband quite relished being Protestants among Catholics, and recalls the young Catholic woman who knocked her door. The young Catholic was embarrassed, because she had been told the previous tenants had already left: the tenants then did leave, speedily, one eye on the vigilante-types supervising handovers. A genteel form of ethnic cleansing but not to be argued with, all the same.
"All of a sudden the top of the Springfield Road was Catholic," another woman recalled last week, "and Springmartin and Highfield were Protestant. On Friday things were fairly normal, by Tuesday the whole world had turned around."
One group had nowhere to go: "the mixed couples." They scattered, some to towns like Antrim and Carrickfergus, others to England. There are fewer marriages now than in the 1970s, and no estimate of "mixed couples" beyond the 10 per cent that government household surveys have recorded for decades.
It is clear only from the Housing Executive's waiting-list, and the veteran NI Mixed Marriages Association, that problems remain, if slightly less dramatic as the Troubles fade. Integrated schools are oversubscribed but sited where they are at least theoretically accessible to most centres of population. Some question the degree of genuine integration in middle-class streets, but it has always been easier for the more affluent to buy or rent away from the places most scarred by violence.
The greatest Northern housing problem is undoubtedly the waiting lists in north and west Belfast, where overcrowded Catholic neighbourhoods sit beside Protestant districts with shrinking, defensive and territorial populations. Moving out of the city is not what most want or are able to do.