Sweden is moving to ban marriage between close cousins. Such bans were once common, but oddly enough some have been rescinded as laws around marriage have been liberalised. However, sometimes we discover that certain prohibitions were introduced for good reasons. Traditionally in the West, close cousin marriage has been banned for genetic reasons, but historically another purpose existed; to weaken the grips of clans on their members and on society.

Sweden is looking to prohibit cousin marriage because immigration from certain parts of the world is reintroducing clans into the country. Clans and cousin marriage are still extremely common in places like Pakistan and Afghanistan and can have all sorts of destructive effects, not least leading in some cases to forced marriage, honour killings, and to widespread nepotism.

What Sweden is seeking to do is what the Catholic Church did centuries ago. In the Middle Ages, the Church sought to ban cousin marriage even to the seventh degree of separation, something that was hard, if not impossible, to pull off in small, tight-knit communities where people rarely strayed far from where they are born.

A recent book that was a real eye-opener for me on this topic is ‘The Weirdest People in the World’ by Harvard academic, Professor Joseph Henrich. ‘Weird’ stands for ‘Western, Educated, Industrial, Rich, Democratic’.

Professor Henrich says that people who live in Western societies are far more individualistic than the world average and he puts this in no small part to the weakening of the clans. Furthermore, he argues that the weakening of the clans made the rise of modern societies and democracy possible. If your main loyalty to is your clan and its elders, it is very hard to develop any kind of loyalty to the nation-state and to recognise any leaders who are not related to you.

This is a chief reason why America found it impossible to suddenly turn Iraq or Afghanistan into modern, democratic States; the clans and loyalty to the clans was simply too strong.

Professor Henrich, who is not religious as far as I know, gives massive credit to the Church for weakening the grip of the clans through its ban on cousin marriage.

Another person who does so is Dr Patrick Nash of Oxford University. He has strongly argued in favour of banning cousin marriage and has been widely read on the matter.

A very recent paper he wrote for the Oxford Journal of Law and Religion is called ‘The Case for Banning Cousin Marriage’. It is, like the Henrich book, a real eye-opener.

He has written on a similar theme in ‘British Islam and English Laws’. In a chapter on the nature of clans he reflects on the effect of the Church’s ban on cousin marriage.

He says that Church opposition to cousin marriage “was a defining feature of medieval Christianity and the cumulative effect was the effective destruction of the extended kinship group. In so doing, it broadened networks of trust; reduced nepotism and corruption, hierarchical obedience and ethnic conflict; permitted romantic love based on individual choice; reattached loyalty to impersonal, rule-based national institutions; all of which are necessary for the large-scale cooperation and coordination upon which the formation of modern democracy depended.”

In the West we take the nature of our societies for granted. We think we are ‘normal’. We forget why we are not clan-dominated in the way much of the world still is or was until very recently. A big part of the reason is the Catholic Church, which is contrary to the widespread impression that modernity is built on the bones of the Church.