Why is the NHS praising cousin marriage?

A week ago, NHS England’s little-known Genomics Education Programme published an article entitled: ‘Should the UK ban first-cousin marriage?’ Over the weekend, the Telegraph reported on the piece, drawing particular attention to its claim that there are ‘benefits’ of first-cousin marriage, supposedly ‘including stronger extended family-support systems and economic advantages’.

The NHS has now deleted the article following a predictable backlash. It eventually issued a statement saying that it ‘should not have been published’. A spokesperson added that ‘the NHS recognises the scientific evidence that there can be an increased risk of children having certain conditions when parents are consanguineous, and the health service seeks to advise and inform patients of these risks in a respectful way’. Which is a relief.

The article was aimed at clinicians rather than the general public, and it purported to be summarising the debate to help inform them. This makes this whole situation far more concerning. This is the quiet guidance and ‘education’ the NHS provides to its staff – and it was only deleted following wider circulation.

The article itself is deeply misleading and the anonymous author does not seem to have properly understood the research it cites. For example, the article refers to the BBC’s reporting of the Born in Bradford research project, which since 2007 has tracked over 60,000 people from Bradford, where first-cousin marriage is ‘fairly common’. In 2013, it found that of the 5,127 babies of Pakistani origin in the study, ‘37 per cent had married parents who were first cousins’, compared with ‘less than one per cent of married couples nationally’. A year earlier, the BBC reported that cousin marriage was on the rise in Bradford, noting that this would have ‘important implications for health’.

What’s more, these health implications are well understood. According to a 2024 study, children of first cousins are almost three times more likely to die by age 10, 20 per cent more likely to attend A&E, and are 90 per cent more likely to have learning difficulties.

Despite this, the NHS’s Genomics Education Programme article tried to minimise the risks, stating that ‘although children of first cousins have an increased chance of being born with a genetic condition, that increase is a small one… from around two per cent to three per cent; this increases to four per cent to six per cent in children of first cousins’. These may indeed sound like small proportions, but these figures also make clear that you double the risks of genetic conditions by having children with a first cousin. The NHS’s decision to ignore the robust mortality and developmental data is also worrying.

The motivation of the author is given away when a British Society for Genetic Medicine report is cited, which ‘warns that… focussing on cousin marriage in this way stigmatises certain communities’. In Britain, first-cousin marriage is especially common in Bangladeshi and Pakistani-origin groups.

Citing the same report, the NHS article claims that ‘research into first-cousin marriage describes… potential benefits, including stronger extended family-support systems and economic advantages’. But it plainly does not support that claim. The article links to a 2022 paper which used genealogical data, meaning it did not study genetics or consider developmental issues. The researchers studied ‘two human populations with high frequencies of cousin marriage’ – the Dogon from Mali and Ancien Régime nobility from Europe. It is hard to understand how the marriage and inheritance practices of inbred European monarchs, or polygynous subsistence farmers from West Africa, might have any relevance to parents in Britain in 2025.

Worse, the research doesn’t actually show ‘potential benefits’ in anything like the way the NHS suggests. All the 2022 study shows is that ‘inbreeding costs – mainly in offspring survival during childhood – in both sexes, in both populations’, but that there are ‘some benefits of cousin marriage, mainly in fertility and age at first reproduction’. In plain terms, societies in which first cousins marry have more children, younger, who are less healthy and more likely to die in childhood. It is astonishing that the NHS misrepresented the study so gravely.

This isn’t about science. The data is clear that cousin marriage, particularly repeated cousin marriage through generations, means that children are more likely to be born with worse health and their development will be harmed. The refusal of NHS staff to acknowledge this – especially those who are supposed to be educating their fellow clinicians – is horrifying. It shows they are more concerned about not offending certain groups. This is a damning sign of a society that is rejecting reason and truth.

The article may have been removed, but an attitude that puts pandering to identity politics above medical science, remains writ large in the NHS.

David Shipley is a writer. Follow him on X: @shipleywrites.