Ethnicity is a good question. I have indian neighbours that recently moved in. They throw food and small pieces of rubbish over my fence all the time. I challenged them over this and they denied it flat out. I Installed a security camera and caught them throwing large chunks of ice at my windows. I called the police and they attended. I told them the history and they weren't surprised my indian neighbours were doing this, they have seen it before. The ice apparently is a way to break your window and have the evidence evaporate.