Europe is starting to lose its patience with so-called cousin marriage. Norway has already banned first-cousins from marrying. In Sweden, a ban is due to come into force this year if parliament passes it, and Denmark is moving in the same direction. Even Tennessee in the US has moved to outlaw marriages between first cousins. And if you’ve not guessed it already, Britain keeps dithering as if this it was all too awkward to touch.

It isn’t awkward. It’s disgusting. It is an outdated, barbaric and un-British practice, and it persists here in the UK on a meaningful scale because the authorities have decided that criticising harmful practices is “cultural insensitivity”, rather than basic moral clarity. First, the unglamorous bit: the public-health reality. The medical literature is clear that consanguinity – where parents are related – increases the risk of inherited conditions and congenital anomalies. And the risk grows when cousin marriage repeats across generations – which is exactly what happens in communities where marrying within the family is treated as the norm.

Britain’s best evidence comes from Bradford, because, unlike most places, the West Yorkshire city has tracked outcomes. The ‘Born in Bradford’ cohort has followed thousands of children and found higher rates of congenital problems and greater use of healthcare among children born to related parents – even when researchers account for deprivation and other factors. In plain English: more GP visits, more referrals, more pressure on services, more misery for children and more cost to taxpayers.

Mortality analysis points in the same direction, with close-relative parentage over-represented in deaths linked to genetic anomalies. All of which is why it’s surreal to watch parts of the public sector tiptoe around this. NHS trusts have advertised specialist ‘genetic risk’ roles to support families in communities where close-relative marriage is common. Labour health minister Dr Zubir Ahmed has told MPs NHS England was funding extra midwifery, genomics and neonatal capacity in high risk areas. In effect, building NHS infrastructure to manage a practice we refuse to confront head-on.

In Britain, this is primarily an issue in Pakistani-heritage communities, alongside other smaller groups. There is no neat national dataset, but local research has repeatedly shown a high prevalence in certain areas.

In parts of Bradford, for instance, “nearly half” of Pakistani-heritage mothers were married to a first or second cousin. ‘Born in Bradford’ data suggests the share of British Pakistani couples who were first cousins fell from about 39% in the late 2000s to about 27% by 2019. That’s a real shift, and it’s good news, but it’s still far above anything resembling normal.

Moreover, health is only half the story. The deeper issue is social cohesion. Marrying within the family is not a quirky eccentricity, like putting mayonnaise on your chips. It’s a mechanism for tightening the grip of the clan – keeping property, loyalty, secrets and power inside an extended family network. That can mean stronger patriarchal control, more pressure on women, and fewer realistic exit routes without the threat of ostracism.

It also slows integration for a simple reason; marriage is one of the strongest social bridges a society has. When marriage is repeatedly restricted within a family, you limit genuine ties to outsiders, and reinforce internal enforcement over external accountability.

Some researchers argue that closed kinship structures create the conditions where grooming-gang scandals become harder to expose; not because every family is criminal, but because dense networks encourage silence and punish dissent. We’ve already seen what institutional cowardice looks like in this country when authorities convince themselves it’s safer to look away than risk being called racist.

Enforcement is the obvious sticking point, and we shouldn’t pretend it’s simple. People will ask how you police a ban on cousin marriage – whether couples will just avoid civil marriage, and what the penalty would be. Those are real questions, but they aren’t a reason to carry on as normal.

A ban matters because law is not just a set of handcuffs; it’s a signal about what modern Britain considers acceptable. It draws a clear line that makes it harder for coercive family structures to hide behind official silence. A liberal society does not mean a society with no standards. It means a society that protects individual freedom. If Scandinavia can say plainly that cousin marriage is bound up with honour oppression and negative social control, then Britain can too.

We should ban it, not because we want to moralise about anyone’s identity, but because we refuse to keep paying, medically and socially, for a practice that is both avoidable and gross.