McCullough and McCulloch Y DNA Studies

The elusive origins of surnames like McCullough, McCulloch and their variants have presented a number of riddles for genealogical researchers and history buffs. DNA testing sites like or 23andMe can be helpful in genealogical research, can provide recent autosomal DNA matches to close relatives, but are limited in providing clues to family origins going back more than a few generations. Such sites are a good place to start building a family tree, glean from compiled historic documents, and get a sense of one’s ethnic background.

In the case of McCulloughs and McCullochs of several spelling variations, it is known that the surname is of Celtic origin, originating in the British Isles. However, it is not clear if the surnames had a common origin that subsequently was “localized” in Galloway, Ulster, and beyond, or if some of the names had distinct origins, but blended into somewhat standard spellings. However, we can say with confidence that not all McCulloughs and McCullochs shared a modern common ancestor. According to the McCollough Project at FamilyTreeDNA, there are currently eight known Haplogroups among “McCollough” males who submitted results of Y chromosome DNA tests.

Wheras autosomal DNA results provide an “ethnicity estimate” which is very open to interpretation, Y DNA results allow a male test-taker to trace his paternal line for many generations. By comparing the Y DNA results of McCollough males and comparing paternal line family trees, project participants can get a clearer picture of which line of McColloughs they are genetically related to.

By taking a Y DNA test and joining the McCollough Project, a participant can determine which family line they genetically relate to. But, even if one is not a member of the same Y DNA haplogroup, this doesn’t settle the issue of identity, affinity, and what might quite loosely be called kinship. Traditionally, not all clan members were related by blood. So, it seems that “Scots-Irish” McCulloughs, McCullochs, McCullohs, et al who identify with the clan may still have a familial sense of solidarity and shared heritage regardless of Y DNA results.