The Macnab surname DNA study is an ongoing project open to any male descendant with either the Macnab surname (or any spelling variant) or the surname of one of the accepted Macnab septs. We have multiple objectives, including identifying a genetic signature or signatures, clarifying the descent of the cadet houses, casting light on the Clan origin theories and the Sept proton theories, and assisting clan members who wish to find matches with individuals or families who share a common male ancestor with the Macnab surname.