MP’s call to ban cousin marriage is prejudiced

On January 2nd, The Guardian posted a letter from a doctor about cousin marriage:

I find it intriguing that a Conservative former minister, Richard Holden, has called for first-cousin marriage to be banned in the UK. He argues that the practice threatens women’s freedom and leads to birth defects. Medical evidence shows that while the risk of birth defects is relatively higher among children born to consanguineous parents, the absolute risk remains low. In fact, the absolute risk increase is comparable to factors such as older maternal age, obesity and smoking – but there are no calls to ban them.

As a GP working at the Royal Hospital for Neuro-disability in London, I manage patients with genetic disorders ranging from Down’s syndrome to rare mitochondrial and genetic diseases. None of my patients were born of consanguineous parents.

I would also like to point out the historical inconsistency in the values being defended – Holden fails to mention that cousin marriage was once a common practice among the British aristocracy.

Stop worrying about cousin marriage

On April 22nd UnHerd had an article about cousin marriage:

Cousin marriage isn’t unnatural: it has been practised around the world for thousands of years. But could it pose a health risk to the resulting children? If Darwin were alive today, he might be surprised to discover that, despite our better understanding of genetics, significant gaps in our knowledge remain. Roughly, the baseline risk of unrelated parents having a child with a major birth defect is 3%; for a child of first cousins, this risk increases to 6%. This means that the vast majority of children born from consanguineous marriages will be healthy. Of course, if there are known genetic disorders within the family, then this risk increases, and successive generations of cousin marriage can also compound the likelihood of having a disabled child — but this is by no means inevitable.

Nevertheless, these additional risks can be offset through prenatal genetic screening, which is currently offered to other at-risk groups. Older pregnant women, for example, are screened for Down’s syndrome, as are couples who are carriers of cystic fibrosis. We don’t ban these individuals from marrying or having children, and we don’t consider them a burden on the healthcare system.

Nor is it only the children of cousins who are at risk. The likelihood of health problems is increased whenever there is a higher chance that two individuals share genes. This can occur in small populations or in any close-knit community that marry among themselves — such as the UK’s Jewish community, or else the Amish in America or French Canadians. Would Holden also support banning marriage within other ethnic communities? I suspect not.

What happens if cousins have a baby?

In 2023 Resto NYC had an article about cousin couples:

When cousins have a child together, there are some elevated risks of genetic problems and birth defects. However, risks are still low in most cases, around 4-7% for first cousins. Major disabilities are very rare unless cousin marriage has occurred for multiple generations. The bigger challenges tend to be the social disapproval and stigma. Cousin couples planning children need to get genetic counseling, understand laws, and prepare emotionally. Overall, cousins can safely have healthy children together in most instances, as long as they are aware of the small risks and challenges involved.

16 Reasons Why It is Okay to Have a Crush on Your Cousin

In 2024 Refurbished Mag had an article about crushes:

Alright, buckle up folks, because we’re diving deep into a topic that’s sure to raise eyebrows: having a crush on your cousin.

Before you start judging, let’s hear it straight from the source—real people, real experiences.

I’ve gathered insights from 16 individuals in similar situations, and let me tell you, the reasons they’ve given might just challenge your preconceived notions.