Board Thread:Episode Discussion/@comment-410526-20160702223237/@comment-28288412-20160704174006

Gastropod wrote: They might not necessarily be related or antiethetical, but I do think they could work by similar principles or mechanism. The Schnees are capable of creating creatures to do their bidding. I think it's possible Salem is able to do the same but on a much, much greater scale, and that's what the Grimm are. Possible.

But it is also safe to assume their are additonal methods of Grimm creation, as highlighted by the Grimm Dragon. If I had to guess, under the theory that Salem created the Grimm, she created a few powerful 'Grimm Mothers' who then go on to create the rest of the Grimm.