Also, the environment and predation plays a role in monogamous behavior. Penguins are monogamous and have shared parenting because one parent has to be with th

Also, the environment and predation plays a role in monogamous behavior. Penguins are monogamous and have shared parenting because one parent has to be with the egg or chick at all times lest the egg/chick freeze or be eaten by predators. Pretty much the environment leaves no room for polygamous or inattentive penguins as their offspring and hence their genes don't make it.