I, for one, wish there had been discussion prior to your relegating a good part of the lists in this article to "Talk:List of coupled cousins/workspace."
This article was established (in August 2007) not as a "list of coupled first-degree cousins" — which you have turned it into — but as a "List of coupled cousins."
It was intended, if anything, not so much as an adjunct to medical studies as to sociological ones.  In some cultures, there need not even be an established familial relationship for a societal one to be regarded as existing:  unrelated individuals bearing the same surname are considered to be "related."
What percentage of a given general population bears what degree of genetic relationship to each other is not the point.  This was conceived as a list of prominent individuals known to be linked maritally or romantically to a cousin, nephew, niece, aunt or uncle.