You wouldnt happen to be Muslim would you?
What's odd about the term "blood relatives" to refer to descendants of one's ancestors, as distinct from "relatives by marriage" (e.g. lying, adulterous husbands)?
Americans know what "blood relatives" means. Anyone who thinks it has something to do with muslims obviously isn't familiar with phrases commonly used in the US.
Blood relatives is a term as you know that is used often in the legal profession when attorneys are trying to sort out who's related to whom. The poster suggesting the phrase blood relatives is indicative of a religious heritage is indicative of their lack of knowledge re: lawyer's lingo.