Marrying a cousin is usually considered a bad idea, because inbreeding can lead to harmful genetic conditions. But paradoxically, in some societies, marrying a related spouse is linked to having more surviving children, research suggests.

Is it OK for cousins to marry?

In much of the world, consanguineous marriage between cousins is very common. For most Americans, however, marriage between cousins is at best a punchline, at worst a taboo. In many states, it is illegal for first cousins to get married. The objections are ostensibly based on the risk of genetic problems.

How bad is marrying your cousin?

Children of first-cousin marriages have an increased risk of autosomal recessive genetic disorders, and this risk is higher in populations that are already highly ethnically similar. Children of more distantly related cousins have less risk of these disorders, though still higher than the average population.

Is it bad to marry your first cousin?

Second cousins share 6.25 percent of DNA while third cousins share 3 percent. The percentage increases more if the offspring of first cousins marry another first cousin.