What we should do when people stare at us diferently or with their nose in the air?

What we should do when people stare at us diferently or with their nose in the air just because we are from another Country?For example Im from Portugal and lots of people thinks that im from Poland trying to disrespect and sometimes people who I dont know from any part ask me where Im from and I assume like disrespectful.I think that London is diferent because there are more variety of cultures but in places like midlands or North of Uk its harder because in here it seems that they are all cousins and who isnt like them its against them.Another example is rare to found a black person in here ,why?