When twins marry twins and have babies, the children are legally cousins, but genetically, they are more like siblings.
Here's a breakdown of what happens genetically and legally:
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Genetic Similarity:
- Identical twins share nearly 100% of their DNA. When two sets of identical twins marry, each couple's children inherit a very similar genetic makeup.
- Since each child gets half of their DNA from each parent, and the parents in each couple are genetically nearly identical, the resulting children end up with a high degree of genetic overlap, similar to siblings.
- In essence, the children are related as "quaternary twins."
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Legal Status:
- Legally, the children are considered first cousins. This is because each child has different parents (even though those parents are genetically extremely similar). Legal definitions are based on parentage, not solely on genetic relatedness.
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Example:
- Consider two sets of identical twin sisters, Amy and Becky, and Cate and Dana. Amy marries Cate, and Becky marries Dana. If Amy and Cate have a child, and Becky and Dana have a child, those children are legally cousins. However, because Amy and Becky are genetically identical, and Cate and Dana are genetically identical, the children will have a genetic relationship closer to that of siblings.
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In Summary:
- The children of identical twin pairs marrying each other are cousins legally, but genetically closer to siblings. They share a higher percentage of DNA than typical cousins would.
