Kinship marriages possibly protected against disease

Kinship marriages may in the past have been effective protection measures against diseases such as malaria and leprosy. In areas where these diseases were rife, a relatively high number of kinship marriages occurred. This has been revealed by research conducted by social psychologist Ashley Hoben. In the West, the dangers of kinship marriages are exaggerated, states Hoben. She was awarded a PhD by the University of Groningen on 14 July 2011.

Charles Darwin, Albert Einstein, Edgar Allan Poe and Queen Victoria all had something in common – they all married one of their cousins. These famous people are respected the world over. However, the majority of Westerners condemn kinship marriages and consider them incestuous, Ashley Hoben’s research has revealed. Women in particular regard kinship marriages as dangerous for the health of the children. However, when the two partners love each other, people , particularly women, have a less negative view of kinship marriage.

Adaptation strategy

The children of kinship marriages have on average one and a half times as much chance of developing health problems and congenital defects as children of unrelated parents, epidemiological research has revealed. This may not always have been the case, however, Ashley Hoben’s research reveals. Historically, in areas where diseases like malaria and leprosy were rife, there were a relatively high number of kinship marriages. Kinship marriages also occur more often in areas that are geographically remote, further research has revealed.

Marriage as protection

It’s possible that kinship marriage was a reaction to unfavourable or hard living circumstances, the PhD candidate sums up her results. Hoben: ‘Kinship marriage may have been an adaptive choice. Because good genes were passed on, the immunity to specific diseases may have increased. Now that societies are less isolated, the descendants of kinship marriages are now more susceptible to infections. Nowadays they have more illnesses and disabilities than the descendants of non-related parents.’

Middle East

Although the United States legislates against kinship marriages, it turns out that in some countries in the Middle East they are significantly less negatively judged than in the West. In Saudi Arabia, Jordan and Iraq, marrying a niece or cousin is even regarded as the norm. Hoben: ‘Throughout the world and history, kinship marriage has been regarded in different lights. This is probably the result of cultural norms and convictions. Perhaps one day kinship marriages will be regarded as incest, just as intimate relations between brothers and sisters are today.’

Risks exaggerated

In the West, the risks of kinship marriage are exaggerated, states Hoben. ‘If a mother drinks or uses drugs during pregnancy, the dangers for the health of the child are many times greater. Much less attention is paid to that, however.’ According to the PhD candidate, there are risks, but they vary from family to family. Hoben: ‘The best way to do something about the taboo against kinship marriage is to provide reliable information about the actual risks, which vary from case to case.’

Curriculum Vitae

Ashley Hoben (Canada, 1983) studied psychology and criminology at Saint Mary’s University Halifax. She conducted her PhD research at the department of Social Psychology of the University of Groningen, funded by her supervisor, Prof. Bram Buunk. Hoben is currently clinical director of a detention centre in Newfoundland, Canada. The title of her thesis is ‘An evolutionary investigation of consanguineous marriages.’

Note for the press

Contact: Ashley Hoben, a.d.hoben rug.nl or tel. 06 13729051.