Napoleon abolished France's incest laws in 1810. ..."
Ah Ha! Now we know why the French are the way they are, Incest over a long period of time!
My father says that the reason why the British are so homely is that they live on an island. LOL
Medieval Roman Catholic "incest" laws (usually applied just to royalty and the upper classes) called "incest" things like marrying your brother's widow...or marrying a 5th Cousin (who has almost no genetic link to you--more than anyone else) or various other long distance seeming family relationship. Much of this was done to break up inheritance problems--and it went way beyond what the bible teaches as moral incest.
The Bible forbids: brother/sister, (and half siblings too) parent/child, uncle/niece or aunt/nephew unions. These are the closest relatives genetically--and which (as in the case of this couple) cause genetic defects in the kids. After the Protestant Reformation in the 1500s, laws were changed in Protestant countries to reflect the biblical injunctions, NOT the old elaborate Catholic ones.
Apparently cousins of any sort have never been forbidden to marry in the Bible, though, due to the Eugenics movement in the 1920s about half the US states have laws against 1st Cousins marrying (the other half do not...and no foreign country that I know of forbids cousins marrying (as weird as that seems...to me). I've read that the latest genetic research finds no significant risk of cousins marrying to theeir kids --even though I agree it just doesn't seem right. (Still probably half of our founding fathers, and very famous people in US history, married cousins....as it was extremely common in early America.)
The allowing of "incest" i.e. getting away from the old Catholic definitions of it, and changing the law to a narrow, genetically (and biblically) based definition MAY be what the article is talking about. I simply cannot imagine that in much of Europe there are no incest laws at all.