From the moment we enter this world we begin learning. Life teaches us many lessons. Whether its being taught in school, others actions, or life experiences we are being taught a lesson everyday of our lives. Therefore I believe business and ethics can be taught to anyone who wants to learn about it.
A person can be taught how to be good and ethical, but that's not the dominating idea you find in business school. No matter how many ethics classes you teach, a bad person will always behave badly, but perhaps learn a better way to hide their bad behavior, or even to justify it.