The UK wants to ban first-cousin marriages – but there’s an ethical challenge

A bill that proposes to ban first-cousin marriage in the UK will receive its second reading in the House of Commons on March 7.

The bill, proposed by Conservative former minister Richard Holden, follows the introduction of a ban on cousin marriages that came into effect in Norway in 2023 and a planned ban in Sweden from mid-2026.

Different reasons might be given for proposing to ban first-cousin marriage. However, one significant reason given by supporters of these bans is concern for public health. Holden claimed in his speech to parliament that: “First-cousin marriage should be banned on the basis of health risk alone.”

In the UK, a long-standing research study of childhood outcomes in Bradford, where there has traditionally been a high rate of cousin marriages within the Pakistani community, recently found that children of first cousin parents had higher rates of learning and speech problems and more visits to hospitals and doctors.

The increased incidence of certain genetic illnesses in children of related parents has long been recognised. When parents are closely related, they are more likely to carry the same faulty genes.

If both parents pass on the same faulty gene to their child, the child has a higher chance of developing a genetic illness (about double the risk of parents who aren’t related). The Bradford...

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