I think it is the people and the culture. The culture, because there are so many rules on how you are supposed to behave, which constrain you. The people you are around because your sister seems to have no feelings at all and you do, so when you naturally show your feelings, like any of us would in your situation too, you look like the problem in your culture (because of the rules and hierarchy and the group and all that). Individual feelings don't mean anything, if I understand correctly.