All in the family: Consanguineous marriages are declining

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CHARLES DARWIN MARRIED his cousin, and may have regretted it. The great scientist’s experiments on plants later convinced him of the “evil effects” of persistent inbreeding. In 1870 he wrote to an MP, suggesting that the upcoming national census ask parents whether they were blood relatives. For, as he noted, consanguineous marriages were commonly said to produce children who suffered from “deafness and dumbness, blindness &c”.

Darwin’s request was turned down. Britain did not start keeping records of marriages between first cousins, nor did it ban the practice, as some American states were doing at the time. Instead, British society gradually changed so that marriage between cousins became undesirable, verging on unthinkable. The same is now happening across the world.

Data are patchy, but the trend is clear. In Jordan, 57% of marriages in 1990 were consanguineous, but by 2012 the figure had dropped to 35%. Surveys of Israeli Arabs suggest that 20% of marriages before 2000 were between first cousins, compared with 12% in 2005-09. Consanguineous marriage has also declined in Pakistan, Turkey and south India. It seems to be growing nowhere except Qatar.

Health workers take credit for the decline. They have argued for years that consanguineous marriage increases the risk of genetic disease, on good evidence. One of the best studies is of Bradford, in northern England, where 37% of ethnic Pakistani babies born between 2007 and 2011 were the children of first cousins. Researchers found that cousin marriage doubled the risk of birth defects, from 3% to 6%.

Not all birth defects are serious, however, and a slightly higher risk of medical problems might not always be evident. Besides, there are arguments in favour of consanguineous marriage. In dowry cultures, women who marry relatives usually have to bring less money to the marriage. Parents who are blood relations will raise their children within a tight kinship web which may provide strong support. One survey in Oman showed that a majority of respondents understood the health risks of having children with a cousin, but a larger majority approved of the practice all the same.

Yet cousin marriage is doomed, if only for demographic reasons. In many countries where it is common, birth rates are plunging. In the early 1980s Pakistan’s fertility rate was 6.4 (meaning that a woman could expect to have that many children during her childbearing years). That number is now thought to have come down to 3.4, and UN demographers expect it to fall to 2.4 by the early 2040s. In Iran, the fertility rate has crashed from 6.5 in the early 1980s to just 1.6.

Two academics, Bilal Barakat and Stuart Gietel-Basten, point out that when women usually have five surviving children, a woman can expect to have 25 male cousins. When the average number of children falls to two, that same woman will have just three male cousins, some or all of whom might be younger than she is, and thus ineligible as marriage partners. The marriage squeeze will be even tighter in cultures that insist, for example, that a woman marry not any old cousin but her father’s brother’s son. Eventually, cousin marriage will be crushed not by medics but by mathematics.

Special report: A looser knotMore in this special report:
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Julio Marchi ©

Publisher / Editor at BS News & Media Services
A free thinker, not labelled as anything, not associated with any party, not part of any group or engaged with any religion... A simple guy tired of the nowadays bullshit who decided to promote more serious debates about what is really happening hoping to bring back intelligence to the superficial and shallow news & headlines that unfortunately took over the existing media scene.
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