Behavior, because it's so complicated to orchestrate, is polymorphic-it requires the action of many genes in concert.
These genes are involved in immune response, and are extremely polymorphic.
British Dictionary definitions for polymorphic
having, taking, or passing through many different forms or stages
(of a substance) exhibiting polymorphism
(of an animal or plant) displaying or undergoing polymorphism
a species of animal or plant that exhibits polymorphism
any of the crystalline forms of a chemical compound that exhibits polymorphism
Also called polymorphonuclear leucocyte. any of a group of white blood cells that have lobed nuclei and granular cytoplasm and function as phagocytes; they include neutrophils, basophils, and eosinophils