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.