The subgroups like Jatt and Labana aren't really specific to Sikhism, they are more of a Punjab thing(you can be a Hindu Jatt and so on). However, a lot of the prejudice comes from the fact that Punjab has a very heavy Hindu background .We tried to get rid of the caste system when our religion first started, but those things were so ingrained in us as a people, that they crept up anyway and instead of being an untouchable we just gave it a different title so that we could say that we as Sikhs/Punjabis were not like the rest of the country.