User blog comment:ProjectPredacon/Grimm from Dust?/@comment-3146930-20150112174046

I don't think so. Dust appears to have elemental properties for the most part so for Grimm to fuse with Dust, but loose any kind of elemental powers seems somewhat disappointing. There is also the fact that they mention Hunters can use their Aura to activate Dust crystals. Grimm on the other hand are said to be soulless so going by your theory, they wouldn't be able to use the thing they are trying to fuse with.

For me, the opening narration claims that people were born from Dust (different from Dust in the show). This could mean that Grimm came from the same thing humans did. This also ties into my theory that the planet itself may have a type of Aura itself, like a living planet. Grimm were born from Dust, so it created Humans using the same primordial soup, but blessed them with souls.

I don't think the Grimm were made in the same way you are suggesting because Grimm seem to have been around before humans, so the negative emotions of humans couldn't create them. However it is basically the same as the chicken and the egg question.