First-Cousin Marriage Is Bad, Even When Muslims Do It

In defending first-cousin marriage for UK Muslim communities, the NHS chooses to prioritize politics over public health.

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About the Author

Dr. Colin Wright is an evolutionary biology PhD, Manhattan Institute Fellow, and CEO/Editor-in-Chief of Reality’s Last Stand. His writing has appeared in The Wall Street Journal, The Times, the New York Post, Newsweek, City Journal, Quillette, Queer Majority, and other major news outlets and scientific journals.

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In late September, the UK’s official NHS Genomics Education Programme published a (now deleted) blog post praising the supposed benefits of first-cousin marriage. It highlighted how such unions can “strengthen social ties,” “preserve family wealth,” and consolidate resources. But it downplayed the well-documented genetic and public health risks that come with marrying a close relative. The timing of the post—amid growing political tensions over immigration and integration, especially within Britain’s Pakistani and Muslim communities—made it even more controversial. To many, it reflected a familiar pattern: progressive institutions that are ordinarily quick to condemn unhealthy or harmful behaviors suddenly become deferential—even celebratory—when those behaviors occur within groups they regard as “oppressed.”

Over the past decade, I’ve become well acquainted with this kind of selective framing, where political bias and double standards seep into what should be straightforward discussions of science and risks. We saw it vividly during the COVID-19 pandemic, when mass gatherings were condemned as reckless and dangerous—except when they were for “racial justice,” in which case they were recast as “essential” to public health. It’s a serious and growing problem, and one that undermines trust not only in our shared institutions but in science itself.

The NHS article begins by noting that first-cousin marriage has been legal in Britain since the reign of Henry VIII, and that the government has “no current plans to change the law.” It mentions calls for a ban—notably from Conservative MP Richard Holden, who described the practice as a “public health issue” and “a threat to women’s freedom,” citing evidence that some women are pressured into such unions. But after this brief acknowledgment, the tone of the essay softens. Under a section called “Is cousin marriage really the culprit?,” it claims that while genetic risks are real, they are relatively small—rising from about 2–3 percent in the general population to around 4–6 percent among children of first cousins—and that “most children of first cousins are healthy.” It warns that criticism “stigmatises certain communities” and instead recommends “genetic counselling,” “premarital genomic testing,” and “targeted health education” as solutions.

The tone softens even further in the section titled “Balancing culture and science.” In it, the article points to the supposed “benefits” of cousin marriage—like stronger family support networks and the ability to keep wealth and property within extended families. It then compares the genetic risks of inbreeding to those from unrelated factors such as older parental age, smoking, alcohol use, or fertility treatments—none of which, it notes, are banned in the UK. By framing cousin marriage as just another “risk factor” and focusing on the need to avoid stigmatization, the NHS seems to have shifted its priorities from warning the public about preventable health issues to defending harmful practices in the name of social inclusion.

The phrase “balancing culture and science” is revealing. Would the NHS urge such “balance” if the culture in question were, say, white rural Britons in Somerset? Would it highlight the “economic advantages” of a practice known to increase infant mortality and rare genetic diseases if it were common among working-class English families? It’s difficult to imagine. But when the same behavior occurs in immigrant or Muslim communities, the tone shifts from caution to indifference, or even celebration. This is the double standard many now describe with the phrase “two-tier Keir”—the perception that British institutions, under a Labour government led by Keir Starmer, apply one standard to native-born citizens and another, gentler one to certain immigrant groups.

As a biologist, I think it’s important to step back from the politics and give people a clear picture of the actual science. The debate around cousin marriage has become such a political taboo that few seem willing to explain what’s really at stake from a public health perspective. So before we can have an honest discussion about whether this practice should be tolerated, discouraged, or banned, we need to understand what inbreeding does at the genetic level and why it carries real risks for human health.