I dont know about castes and stuff... but I believe: Hinduism is one of the oldest religions.. since the time when there was no Christanity or Islam. Hence there was no need to convert anyone. Anyone who was born was a Hindu by default. Hence, there is no conversion to Hinduism. There is only conversion to other religions such as Christanity (baptism). Thus, everyone is a Hindu unless they choose to become something else.
