If one identical set of twin women married another identical set of twin men and subsequently had children, their children would genetically be siblings.
![Twin-Sisters-Marry-Twin-Brothers-](https://monkeypickles.com/wp-content/uploads/2014/04/Twin-Sisters-Marry-Twin-Brothers-211.jpg)
It brings a whole new meaning to the phrase “Family Reunion”; just make sure not to get the kids (or spouses) too mixed up.