In an area zoned for single family residence only, regardless of how the home is physically divided or occupied, only individuals related by blood or marriage can co-reside, or at most an unmarried couple still functioning as a single "family" (e.g. two romantic partners and their respective children; the law recognizes that the definition of "family" has broadened). Unrelated, non-romantically involved individuals would violate single family zoning and be illegal.