Is Marriage to a Second Cousin as Harmful as First Cousin Marriage?

Queen Elizabeth II married a second cousin without any significant problems, but this practice is subjected to widespread skepticism in the Anglosphere. Despite its legality in most countries and the lack of a biblical basis for prohibition, marrying a second, third, or fourth cousin could be a safer decision due to fewer chances of genetic disorders.

Popular Misconceptions and Genetic Reality

Many believe that marrying a close relative like a first or second cousin would result in offspring with a higher risk of genetic mutations. This is a myth. Research and studies indicate that such unions do not increase the likelihood of new mutations. Instead, the concern lies with recessive genetic disorders, which can occur in about 3% of the general population.

Recessive Genetic Disorders and Family Relationships

First cousins share about 12.5% of their DNA. However, the risk of inheriting a recessive genetic disorder doubles when both parents carry a defective gene. This means that the risk for first cousins is still relatively low, as around 95% of their offspring will be healthy. For second cousins, the shared DNA is halved, giving a 4-5% chance of passing on a recessive genetic disorder.

Successful Unions with More Distant Cousins

Marriage between third or more distant cousins is the safest option, as studies suggest higher reproductive success and lower risk of genetic disorders. These unions not only produce more offspring but also have more successful offspring in subsequent generations. Therefore, while marrying a second cousin can be risky, it is not as harmful as a first cousin marriage.

Historical Precedents and Exceptions

The Habsburg dynasty is a prime example where marriages within closely related families led to inherited genetic disorders, such as those seen in the Royal House of Spain and other European families. However, this is not solely due to cousin marriages. The same issue arises from repeated marriages between the same family members over generations, compounding their familial DNA, leading to genetic problems.

Social and Cultural Implications

Some cultures discourage cousin marriages, often indoctrinating children from a young age. These societies view marrying a cousin as akin to marrying a sibling, which often leads to ostracization. However, in societies where such practices are embraced or tolerated, there are fewer concerns about the genetic risks associated with cousin marriage.

Conclusion

While marriage to a second cousin is not as harmful as a first cousin marriage, it is still not risk-free. Genetically, second cousin unions are less problematic, and there is evidence that they can even lead to higher reproductive success. However, history and family history should be taken into account, as repeated marriages between the same families can lead to significant genetic issues. Social and cultural norms also play a substantial role in the acceptance and impact of such marriages.