The way Abraham is talked about dwelling in Ur, it still sounds as though he was a foreigner, but it says his father was born there. I don't think it actually says whether or not Chaldeans were a Semitic, a Hamitic, or a Japhetic race, but its possible they were related to Abraham, but not of his direct lineage. Theres also the issue of how related to ancient Chaldeans you actually are, as Islam kinda screwed up a lot of the middle east by moving people around and mixing them together.