[goodwithagun]

Well, that explains a lot.

[Eric in the Ozarks]

Deport every one of them.

[Vigilanteman]

. . . a practice that has been prohibited in the Judeo-Christian tradition since the days of Moses.

It explains a lot, but this part is not true.

19 states allow first cousin marriages under any circumstances. (And, no, West Virginia is not one of them). 25 prohibit it, though unlikely that they can enforce those laws given the recent supreme court redefinition of marriage. The remaining six permit it under certain circumstances, five of which are fairly logical:

1. Arizona- if both are 65 or older, or one is unable to reproduce.
   
2. Illinois- if both are 50 or older, or one is unable to reproduce.
   
3. Indiana- if both are at least 65.
   
4. Maine- if couple obtains a physician's certificate of genetic counseling.
   
5. Utah- if both are 65 or older, or if both are 55 or older and one is unable to reproduce.
   
6. Wisconsin- if the woman is 55 or older, or one is unable to reproduce.

The problem is less an occasional first cousin marriage, which was not at all uncommon in early America, than generation after generation of the same.

[tbw2]

That was one of the side benefits of conquest - sex slaves = new blood.
It is probably also what kept many royal families on top - foreign brides decreasing the inbreeding depression in the clan.