With the possible exception of charades, no element of a British Christmas rivals the Brussels sprout when it comes to dividing families. In any well-ordered family, the sprout is a source of fierce disagreement, with those that love the vegetable on one side and haters on the other. There is no Third Way of the sprout. This gulf of opinion is highly satisfactory for those of us who love sprouts. It transforms a liking into a badge of honour, even gallantry, as we tuck into sprouts like so much green candy while siblings, wives and children turn pale at the sight.

When the Rennie family was first posted to the Belgian capital, a small part of me worried that the ‘Brussels sprout’ would prove to be a linguistic joke, and that they might not exist here at all. It was a needless worry. The Sunday market in our scruffy, friendly borough of Saint-Gilles is not just home to heaped piles of Brussels at this time of year. The market itself stands on what were fields full of sprouts right up to the 19th century. Still better, my corner of Brussels turns out to burst with pride as the birthplace of the global sprout industry. Saint-Gilles’s most notable citizens belong to a fraternity devoted to the sprout, the ‘Confrèrerie des Kuulkappers’, or ‘Brotherhood of Cabbage-cutters’, after the local dialect for sprout farmers.

With Christmas looming, an audience with the kuulkappers seemed imperative. After lengthy contacts, dropping The Spectator’s name secured an interview with their grandmaster, Julien Weckx, as he prepared their annual feast in an ornate inner chamber of the Saint-Gilles town hall on a recent weekend. For their banquet, the brotherhood dresses up in velvet robes and consumes such delights as venison with sprouts, sprouts with bacon and the ‘Boulette des Kuulkappers’ (a meatball wrapped around a single sprout, like a giant savoury gobstopper).

Weckx, a longtime deputy mayor for culture in the borough, offered a secret. No native of Brussels would dream of eating a plain boiled sprout, as the British do. ‘We cook them twice, or three times, really. The first time, you cook them in water and throw the water away.’ That first water is positively toxic, insisted Weckx, a veterinarian by profession. ‘You rinse them with cold water and cook them a second time, and they are a great deal more pleasant.’ Finally, the twice-cooked sprouts are sweated with butter and diced bacon, by which time it is safe to assume they barely taste of sprouts at all. ‘Traditionally, we could cook them for a good half hour. They are good and soft at the end,’ Weckx said. Natives of Brussels do not eat sprouts at Christmas, he revealed. They serve mushrooms and chestnuts with roast turkey, and perhaps a green salad.

The brotherhood takes a dim view of suggestions that the Brussels sprout is a relatively modern import from Asia. Weckx points to the tantalising find of a menu from a 12th-century Flemish nobleman’s wedding, which talks of ‘choux d’Obbrussel’. Obbrussel is the old name for Saint-Gilles, but the reference is ambiguous. In modern French, ‘choux de Bruxelles’ may stand for sprouts, but the phrase only literally means ‘Brussels cabbages’. Those 12th-century nobles may have been dining on sprouts, or cabbage.

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The brotherhood has better proof of cabbage-farming in Saint-Gilles. Belgian judicial archives hold a judgment from 1533, handing down a death sentence to a pig belonging to a local kuulkapper, which had killed and eaten a child. In keeping with the harsh justice meted out to animals at that date, the murderous pig was drawn and quartered alive.

Whole families would live off the produce of a single field, prodding farmers to try to maximise revenues, Weckx explained. They first began planting cabbages under fruit trees; then — in a horticultural version of Manhattan — they went high-rise, realising they could grow more cabbages if they specialised in vertical plants that bore many tiny heads of cabbage on long stalks: in other words, sprouts. Weckx chose his words with care. ‘Saint-Gilles did not invent the Brussels sprout. There is a wild Brussels sprout, though it is a lot smaller. But Saint-Gilles can legitimately boast that it pioneered commercial sprout cultivation.’

True natives do not actually talk about Brussels sprouts. In Brussels, reasonably enough, they are just sprouts, or ‘sprôtches’ in the city’s dialect. Weckx believes that the English term ‘Brussels sprout’ entered common usage thanks to the Battle of Waterloo — one of the first moments when large numbers of Englishmen were wandering around what would later become Belgium. Can it be coincidence, Weckx asks, that during the fateful battle Saint-Gilles was not just full of ‘sprôtches’, it was also the site of British camps, including a military hospital more or less where the Eurostar train pulls in today?

Alas, Jane McCauley, a senior etymologist at the Oxford English Dictionary, has her doubts about the Waterloo theory. ‘It doesn’t really hold water from a dates point of view. We have a reference from 1796, from Richard Weston’s The Gardener’s and Planter’s Calendar. There is a line in that which says that in June you should “sew and prick out at the end of this month Brussels sprouts”,’ she says.

So what about Weckx’s boldest claim: that boiling sprouts once, in the British style, leaves them toxic to humans, or at least unbearably bitter? Paul Breslin, an American geneticist, offers a cautious endorsement. He has studied compounds known as glucosinolates found in sprouts and vegetables like broccoli. These compounds are toxic to people with thyroid problems (though they appear to help ward off cancer in healthy people). They are bitter-tasting and they are broken down by cooking, he confirms. However, there is a catch. In a development that offers the science-minded family the promise of loud disputes this Christmas, geneticists have found that those same compounds do not taste bitter to everybody. In crude terms, about 30 per cent of the population have a genetic quirk that leaves them unable to pick up the bitter taste of glucosinolates. To use more technical terms, Brussels sprouts taste less bitter to people who are ‘homozygous for the AVI haplotype of the hTAS2R38 gene’ — a line you may care to remember for use around the dining table.

This is potentially devastating news for sprout lovers. What if we are merely insensitive freaks, and not brave at all? Reached by telephone at the Monell Chemical Senses Centre in Philadelphia, Dr Breslin warns against concluding that sprout-loving is simply a question of genetics. ‘Tasting bitterness is not the same thing as liking or disliking vegetables,’ he says. Grown-ups routinely learn to love bitter things, especially when they carry social cachet, like coffee or beer.

Yet under prodding, Dr Breslin admits that he is in the 30 per cent of the population who cannot taste bitter glucosinolates. And yes, he loves sprouts. ‘My wife can’t stand them, so when I prepare them, I am on my own.’ Which sounds like the makings of an excellent British-style Christmas.

David Rennie is a contributing editor of The Spectator.

This article first appeared in the print edition of The Spectator magazine, dated