Irish Type III - a Y-STR Signature for Gaelic Dalcassian Families


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Irish DNA Project analysis


Analysis of 25-marker short tandem repeat haplotypes in the Ysearch database reveals a distinctive Y-DNA signature that peaks in frequency in the Irish counties of Tipperary, Clare and Limerick. These counties were the hereditary homelands of the Dál gCais families, also called Dalcassian, septs descended from Cas, born CE 347, sixth in descent from Cormac Cas, King of Munster. Dalcassian surnames are more strongly represented with this signature than other surnames. A Y-STR signature for the northern Uí Néill lineages was previously identified. In the present paper, we present evidence for the signature of the Dál gCais, presently referred to as “Irish Type III.”

Dalcassian Families

MacArthur, O'Beollan (or "Boland"), O'Brien, O’Brennan, O'Casey, MacConsidine, O'Cormacan, Cosgrave, MacCraith, (or MacGrath), O'Curry, Eustace, Glinn, Glynn, Hearne, O'Hogan, O'Hurley, O'Kelleher, O'Kennedy, Magan, Maglin, MacMahon, O'Meara, Muldowney (now "Downey"), O'Noonan, Power, Quirk, O'Regan, Scanlan, O'Seasnain, and Twomey.