What is the point of prohibiting incest?

Hello Rabbi,
I wanted to ask an interesting halachic-principle question:
Suppose two sets of identical twins marry each other (a brother with a sister, and his twin brother with her twin sister). The children of both couples will be cousins, but genetically they are like full siblings.
From a halachic perspective, are these cousins ​​considered ordinary cousins, who are permitted to marry each other, or should we also take into account their biological relationship and see them as brother and sister?