I've never heard about non Asian descent not being able to digest Nori. I even often read that we should not eat too much nori because of the high content of iodine, so I always assumed we could digest it fine?
I also didn't know about Native Americans not being able to tolerate alcohol, but I certainly know it's true for a lot of Asians! Not all of them, because apparantly not all lack a certain gene (Starkad can drink alcohol just fine), but the amount of completely wasted japanee salemen I have seen in japan..
Moi, maybe it's like with the Japanese and only individuals that lack the gene have problems with it and not all.