In the year 1075, under the leadership of Archbishop Lanfranc of Canterbury, an Italian, the Synod of London decreed that marriages with first cousins, sixth cousins, and any cousins in between were forbidden. Nine hundred and fifty years later, in September of 2025, the Genomics Education Programme of the National Health Service of England published a blog stating that marriage between first cousins had “various potential benefits” (mainly to do with “stronger extended family support systems and economic advantages”).
The long view, stretching back to the London synod and beyond (by 1075, the Catholic Church had already been stamping down on cousin marriages for around seven centuries), shows just how far the NHS authors were flying in the face of settled custom—though not positive law—in England. The long view also demonstrates that, if the Harvard evolutionary biologist Joseph Henrich is correct, the NHS was thumbing its nose at a cultural, religious, and social tradition that has benefited Britain enormously. The Church’s cousin ban, according to Henrich, is the Rosetta Stone of all British and Western exceptionalism: the historical event that unlocked the capacity to trust and cooperate with strangers, to resist pressure to conform, to respect rules—all of the peculiar psychological traits on which, Henrich argues, the best of the West was built.
The short view, on the other hand, is far more nakedly political, and tied to the increasing turbulence in British life on the subject of large-scale immigration. Cousin marriages are, in this respect, a new lightning rod for dissension. Approximately 3 percent of all marriages in the U.K. are between first cousins; however, about 55 percent of British Pakistanis, according to a 2021 study, are married to first cousins.
The children of these marriages have an increased chance of being born with genetic conditions and birth defects. Indeed, the NHS blog acknowledged this reality, and also noted that in the northern English city of Bradford, which has a large British Pakistani population, more babies are born with genetic conditions than elsewhere in the country.
Soon after the blog was posted, Wes Streeting, the Labour politician who holds the health brief in Keir Starmer’s cabinet, demanded that the NHS apologize. The post was subsequently pulled. But then, in another twist, Sam Oddie, a neonatologist practicing in Bradford itself, came to the blog’s defense, calling it “very substantially factually based.”
Elsewhere, Matthew Syed, a prominent columnist at The Times (whose father was a Pakistani convert to Christianity), has been using his platform to highlight the problems associated with cousin marriage, while expressing support for a Conservative MP who has brought forward a private member’s bill seeking to ban the practice. Syed has also posited that cousin marriage was the cement that bound together members of the so-called “grooming gangs” that have been committing child rape in certain English towns and cities for decades (a scandal that attracted the eye, and with it the ire, of Elon Musk).
The discussion of the consanguinity issue points toward wider trends—in particular, changes that are taking place in what is doable and sayable in Britain. Even the most casual observer will note that more and more people are starting to worry that English society is morphing into something unrecognizable. Today it is cousin marriage; tomorrow it could be polygamy, or honor violence, or female genital mutilation, or face coverings (which the governments of Italy and Portugal are now moving to ban).
In an increasingly febrile atmosphere, these cultural practices—seen as unwelcome intrusions into the English way of life and engines of division—provide the disillusioned with stark, simple test cases for establishing the parameters of what the political classes, and especially the main political parties and their leaders, are prepared to say or not to say, to do or not to do. If mainstream politicians are seen to dither and obfuscate, or to look the other way, or to reach only for soft power solutions—more reviews, more research, more education—a further hardening of hearts and minds seems inevitable.
And, with this, the road to Downing Street for Reform, Nigel Farage’s insurgent populist party, straightens, clears, and widens even more than it already has (if, that is, opinion polls turn out to be a reliable guide to how people will actually vote); the humiliation of the Tory and Labour behemoths becomes an even stronger prospect. However, the next general election in the U.K. is not due to take place for just under another four years. Until then, it’s not going to be an easy ride for anyone.
