User blog comment:Theory of everything/Grimm Speculations Part Two: Evolution and Transformation/@comment-1509826-20120422113539

wow, I have one critism, all this talk about wesen's mating with humans, now I might be wrong, but Humans can't even mate with are closest living relative, and theres only a three percent differance between us,

While many wesens, clearly have Canine, Feline, Reptile, Bird and Arachnid DNA, for that to be true, it would consist they have a larger differance in there genetic makeup than three percent, thus making breeding impossible.

Now I'm no expert so I maybe wrong, and if I am will someone please note it, but as far as I know those facts are true, so breading between the two is genetical impossible.

Then again, it is a fantasy series so I guess they can ignor centain laws of science.