This one is from WickedJuggalette429! Enjoy!
If two sets of identical twins - boy, boy, girl, girl - had one child, each couple's child would look identical.
Or, if that was confusing: There are two identical boy twins and two identical girl twins, and if both of the girls go to one of the boys, and have a child, each child would be identical!
Cousin twins!
Vote, co-You know it already.
p.s. If you don't want to read all of them, you can skip to Fact #1, and then read through them all, if you like, which you will, because, duh, I wrote it.