Kok is not a deformation, It's found in many pure species, mostly Amphilophus. Short body, bonsai, parrot beak, missing fins, etc are deformations. Both Pure species and hybrids can get these deformities. But I've only seen the parrot beak in hybrids. The deformities come from many generations of inbreeding(besides parrot beak which is a result of hybridization). I think a common misconception with deformed fish is that many people think deformed fish = suffering fish, Which is not necessarily true.