I was just thinking about castes. I am not sure about how caste and different ethnic groups work, or caste inside the same ethnic group. But let's consider the latter: In caste systems that passed from generations during great time, how did those castes came up?
How did they form themselves? Why some people became artisans, nobles, governors, warriors, priests, royal family, and stayed that way for generations?
Were the differences merely decided in some time of turmoil, with each person from the same race leaving together and slowly changing the system of society towards the caste model, then slowly forming and settling through the years the peoples and families of the castes?
Was there any similarity or relationship between personality types, intelligence, etc., that related a person to his caste? Was the appearance different?
Was it common for a person to move from his caste, or for a family to go change caste?