In Defense of Cousin-Marriage

	According to Robin Fox, a professor of anthropology at Rutgers University, it's likely that 80 percent of all marriages in history have been between second cousins or closer  but the practice has fallen out of favor in recent times [^1]. American law in particular treats first-cousin marriage as less a principle than a patchwork: banned in 24 states, permitted in 19, and allowed only under peculiar conditions in the rest. 
First-cousins on average share 12.5% of their DNA which leads some to question the practice due to dangers of genetic disease. A Born in Bradford study found that consanguineous marriages had a risk rate of 6.1% compared to 2.4% in the general population studied: only a 2-3% increase [^2]. This compares to a  4% risk for white women over 40. 
If such risks do not justify prohibiting older women from having children, it is unclear why they should justify prohibiting first cousins from marrying. Furthermore, people with recessive diseases or elevated genetic diseases are not prohibited from reproducing eg. Huntingtons patients who have up to 25-50% chances of passing on a debilitating disease [^3] [^4]. When you support the restrictions of marriage on a genetic basis, you should rationally support the sterilization of those with diseases and the ban on the reproduction of women over the age of 40. Why should you support one but not the other? But perhaps, the concern isn’t the immediate risk but the cumulative risk from generations of consanguineous marriage. 
Repeated endogamy increases homozygosity and allows harmful recessive alleles to accumulate.Yet this is an argument against sustained patterns of close-kin marriage, not against every first-cousin marriage. The genetic risk of a single first-cousin union depends heavily on pedigree and population history. Indeed, the elevated rates observed in Bradford arose within a community with a long tradition of endogamy rather than from cousin marriage considered in isolation. Even if you were to ban first cousin marriage, members who marry second cousins or apparently unrelated members would still share significant DNA due to the small size of the group.The relevant variable is therefore the degree of shared ancestry, not the legal label "first cousin”.

Moreover, advances in genetic counselling and carrier screening allow many recessive disorders to be identified before or during pregnancy, enabling informed reproductive choices rather than relying on blanket legal prohibitions. Finally, the government should not intrude into such private affairs in the first place. Even if a majority considers a particular relationship immoral, that alone is not sufficient grounds for legal prohibition between consenting adults. History is littered with moral consensus that we regard as prejudiced. Nearly nine in ten Americans regarded homosexual relations as morally wrong in the 1970s; today, that figure has fallen to roughly four in ten. Nearly 96% of Americans disapproved of inter-racial marriages in 1958 and today that has fallen to only 6% of Americans. Moral consensus changed, but the principle of personal liberty did notIn a free society, the burden rests on the state to demonstrate concrete harm sufficient to justify restricting the private relationships of competent adults [^5] [^6]. Another argument for restriction is that possible power imbalances could lead to coercive marriages. But coercive marriages are already illegal; the existence of coercive cases no more justifies an outright ban on cousin marriage than domestic abuse justifies an outright ban on marriage. Imagine two neighbouring families who spend every holiday together. Their children are raised almost as siblings, and the parents openly hope they will marry one day. They eventually do so as consenting adults. Few would object. If those same children happened to be first cousins, why does the moral analysis suddenly change? If the answer is genetics, then the argument should be genetic. If the answer is coercion, then coercion should be combated not the principle of marriage itself.

[^4]: In the past, Buck vs Bell sterilization was forced for disabled people including Huntington’s https://www.eugenicsarchive.ca/encyclopedia?id=535eec597095aa0000000232&view=reader [^5]: https://news.uchicago.edu/story/americans-move-dramatically-toward-acceptance-homosexuality-survey-finds [^6]: https://www.them.us/story/nearly-4-in-10-us-adults-think-homosexuality-is-morally-unacceptable