Cousin Marriage License Laws in the US
“Laws against cousin marriage are not supported by science.
In fact, the health risks of marrying a cousin have been grossly exaggerated.”
This is what Dr. Alan H. Bittles of Murdoch University in Australia.
And he’s not just talking: the geneticist has just published a book on the subject, Consanguinity in Context , which has not yet been published in Brazil.
In the book, he examines what he calls “common misconceptions about cousin marriage” from a legal, cultural, religious and medical perspective.
It’s not a matter of making a big fuss, says the scientist: A better understanding of the health effects eventually arising from cousin marriage could mean better marriage laws and better health care for cousin couples and their children.
Cousin marriage is taboo in much of the western world.
But not in Brazil. Here, according to Article 1521 of the Civil Code, marriage between collateral relatives up to the third degree – uncle and niece – is prohibited, but the so-called first cousins are relatives in the fourth degree.
In the United States, 31 out of 50 states prohibit marriage between cousins, or allow it only under certain circumstances.
The practice is even encouraged in other parts of the world. In South Asia and the Middle East, for example, between 20 and 50% of marriages are between first cousins or even closer relatives.
According to the researcher’s data, more than 10% of the world’s population is married to a second cousin or closer, or has parents who are cousins.
Charles Darwin and his wife Emma were first cousins. Darwin’s grandparents were also cousins.
Risks of Cousin Marriage
Cultures where cousin marriage is accepted defend its social and economic benefits, such as strengthening family ties and maintaining wealth in the family.
Opponents argue that marriage between first cousins increases the risk of passing on genetic abnormalities.
But for Bittles, 35 years of research into the health effects of cousin marriage has led him to believe that the risks of marrying a cousin have been greatly exaggerated.
According to him, there is no doubt that children whose parents are close biological relatives have a higher risk of inheriting genetic diseases. Studies of cousin unions around the world suggest that the risks of illness and early death are 3% to 4% higher than in the rest of the population.
But, continues the researcher, the risks apply mainly to couples who are carriers of genetic disorders, which are usually very rare: “For more than 90% of marriages between cousins, the risk [of having a child with a genetic anomaly] is the same as the general population,” he said.
Furthermore, many studies on the effects of cousin marriage do not take into account the influence of non-genetic factors on child health, such as socioeconomic status, maternal diet during pregnancy, and infections. “A lot of the data is extremely poor,” said Bittles.