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The O’Conor–McManus connection: history and DNA

The historical tradition and genetic findings linking McManus and O’Conor paternal branches.

Published 17 September 2026Research by Kevin McManus
Church ruins and a stone cross at sunset; an illustrative scene for Irish family history.
Church ruins and a stone cross at sunset; an illustrative scene for Irish family history. Credit: Carl Dreher / Unsplash

The O’Conor connection brings together two kinds of evidence: historical genealogies and modern Y-DNA research. Their agreement makes this a useful part of McManus history to explore.

The historical tradition

The Roscommon McManus tradition traces its origin to Maghnus, who died in 1181, a son of Turlough Mór O’Conor (1088–1156). Turlough was High King of Ireland; those dates are his lifespan. FamilyTreeDNA describes this tradition in its O’Conor House connection report.

What the DNA research found

Maurice Gleeson and Kyle DePew’s published FamilyTreeDNA account describes a McManus cluster on R-BY18179 and an adjacent O’Conor cluster on R-FT16709. Their shared branch is R-BY18115. The research compares that branching pattern and its estimated age with the historical genealogies, finding support for the McManus–O’Conor relationship. Read their research account.

My FT194071 report identifies an O’Conor House connection through BY18115, with a shared paternal ancestor estimated around 1050 CE. This is a genetic relationship interpreted alongside historical pedigrees. It does not supply every intervening father and son in my own family history. Source: FamilyTreeDNA connection report.

Following the evidence

The distinction is straightforward: the historical account names people; the DNA tree groups related paternal lines. Comparing them helps test the history, while documentary research remains necessary for individual family links.

Continue with our FT194071 branch, the two McManus septs, Roscommon articles or the Before 1700 timeline. Related research is collected under connections.