Caste and the illusion of identity

While coming by the auto rickshaw this idea hit my mind about the tradition of casteism in India. Now we normally associate a person by his caste. What we really mean is that we tag an individual with a particular identity and associate all the customs and rituals of that tag with that individual. It is like a parent-child concept in Software. The characteristics of that parent completely overshadows the individual. The Hindu society and its peers is divided into a a hierarchy of caste and classes. This, I am told was propounded by Manu and he did this according to the principle of division of labour. But what I don't know is when we started developing prejudices and bias towards individuals of different castes. We should have left the individual scot free and let them do whatever they like.