SIBLING MARRIAGE AND THE LAW
August 14, 2018
[Click here for links to articles and videos by children of anonymous gamete donation and by gays]
[Click here to see my view about same-sex marriage and anonymous gamete donation]
The following links to articles are intended to make it clear why we have laws against sibling marriage and why that is a good thing. Those who--in the context of trying to refute my view about same-sex marriage and anonymous gamete-donation conception that is discussed here--argue that marriage in our society is not at all about procreation, that it is just about a loving and committed relationship between two consenting adults, are driven by the logic of this false premise to the absurd conclusion that there are no good reasons for society to ban sibling marriage. Read the links presented below to see that there is a VERY good reason to ban sibling marriage, a reason that obviously has nothing whatsoever to do with hatred of siblings or "sibling-phobia." The reason is that, in our society, a marriage certificate confers formal social approval (which is not the same thing as legal permission) to produce a child (as opposed to adopting one.)
The Official Reason for the Law Against Sibling Marriage
The reason the U.S. Supreme Court gives for why sibling marriage is illegal is that sex between siblings is illegal (due to the risk of genetic harm to the resulting child) and allowing siblings to marry would mean giving formal social approval for them to do what is illegal and potentially harmful to a child. If marriage had nothing to do with procreation, then the Supreme Court's reason would make no sense. The reason it DOES make sense, however, is because marriage in our society confers formal social approval to the couple to produce a child of their own (as opposed to adopting a child.)
Yes, Siblings Do (or Try to) Marry Sometimes; It's Not THAT Rare
When siblings (or close relatives) first meet as adults and don't know initially that they are siblings (or close relatives) because of separation at birth or soon after, the genetic similarity may (it's an open question) make sexual attraction greater than it would be otherwise, as discussed here and here and here and here . This means that when an anonymous sperm donor has many children who are half-siblings and who don't know they are half-siblings, the likelihood of half-sibling marriages among them may be higher than if they were not so closely genetically related.
The Genetic Risk of Harm for Children of Siblings
Children of siblings are at a higher risk of genetic harm because the probability of the child having a recessive gene from both parents is increased. Every subsequent generation of sibling matings (i.e., a child of a 2nd generation of sibling matings would be one whose grandparents [its the same couple on the maternal and paternal side] were siblings and the parents were also siblings) increases the probability of genetic harm to the child because it increases the genetic similarity between the child's two parents. Laws against sibling marriage are thus especially important to prevent 2nd, 3rd and higher generation sibling marriages, for which the risk of genetic harm to the child is very substantially greater than for a child of a 1st generation sibling marriage. Read about the genetics here and here and here and about the effect of many generations marrying within the family here .