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Gortlassabrien and the Thomond O'Briens

(Updated December 2021) The surname ‘O'Brien’ literally means 'descendant of Brian,' the most notable ‘Brian’ in Irish history being the High King of Ireland ‘Brian Boru.’ Brian Boru was born in the kingdom of Thomond (which includes the modern Irish county of Clare, and parts of neighbouring Tipperary and Limerick). However, an examination of the distribution of the O’Brien surname (and its many spelling variants) reveals at least 16 geographically distinct groups of O’Briens in Ireland and hence potentially 16 genetically unrelated O'Brien clans. So not all O'Briens can claim a truly Royal Brian Boru origin!  It has become one of the most common surnames in Ireland simply because Brian was a common personal name. So how do you determine if you are indeed a Royal O'Brien (directly descended from Brian Boru). To do that you have to take a simple painless commercial ancestral Y-DNA test. The Y-DNA test only explores one’s paternal line, and since surnames arose among tribal groups of related males living in a specific location it means that

'each of the 16 O’Brien Clans will have their own fingerprint of genetically matching surnames revealed upon Y-DNA testing.' The ROYALO'Brien Y-DNA 'fingerprint' of surnames as revealed upon Y-DNA testing is detailed below. The surnames are graded by frequency, such that many O'Briens (91) appear as a DNA match, followed by 31 individuals named McGrath. Those surnames revealed upon Y-DNA testing literally arose among related males living on the County Tipperary and Clare borderlands which is best illustrated in the image taken from the Irish Origenes Surnames map which shows where each Irish surname concentrates in early census data (below right). 

So if you think you are a Royal O'Brien (descendant of Brian Boru) then you must first take a Y-DNA test (contact Irish Origenes to find out where to test click here). When your results arrive, all you have to do is examine the surnames of the males who have also Y-DNA tested and with whom you share a common male ancestor. Do they resemble the surnames detailed below? If the answer is 'Yes' then you are the closest thing to Irish Royalty! If the answer is 'No' then you are an O'Brien from one of the other 15 O'Brien clans (if that's the case contact Irish Origenes for a FREE CONSULTATION click here).   

The O’BRIEN Y-DNA CASE STUDY which can be downloaded and studied by CLICKING HERE demonstrates the DNA pinpointing process quite beautifully. The results are truly revealing, the test subject Mr Joseph O’Brien has a clear Royal Thomond origin (his founding ancestor was indeed Ireland’s most famous Irishman ‘Brian Boru'). Even more remarkably, close to the pinpointed origin one finds some placenames that are clear references to the O’Briens….. could it be the area where Brian Boru was born? There is no way to conclusively prove the link but all the DNA evidence leads to Gortlassabrien

You can contact Irish Origenes by CLICKING HERE for a FREE CONSULTATION on your DNA results or to find out about a suitable DNA test for you. Remember folks, I am a trained scientist; many online DNA bloggers have no formal scientific training, and have never worked in a scientific research lab or interpreted scientific results. Always research the person writing that DNA blog (check their qualifications, an honorary title is just what it says, but it can go to one’s head). 

English Origenes

Scottish Origenes