Limits of genes and/or hediffs

[BebopCola]

Is it possible to use biotech genes and/or hediffs to disable intelligence on a humanlike pawn?

For example, say we're running an old-school group of Planet of the Apes scenario with wandering packs of simple-minded humans who will need to interact/coexist with astronaut humans from the past or underground mutant humans worshiping a nuclear bomb, can that be done simply with genes, or by adding a hediff?

I would expect that one could just create a new "race" type using an animal base and substitute the humanlike textures, but then it wouldn't be the same humanlike race that could make use of biotech's gene system and other humanlike pawn functions.