Friday, August 10, 2012

Genealogy Gold: McCarthy DNA

   Sometimes in genealogy, we go for the gold.  We try to figure out how we are descended from Presidents, royalty or other famous people.  In the US, if your last name were Adams, you might ask if you are related to the second President.  With a surname like Stewart/Stuart you could try to research back to UK royalty.  If you are Irish, some of those royal names are O’Neill, O’Brien or McCarthy.

   The last King in Ireland died in the 1600s.  For many of us it is incredibly difficult to go back beyond the 1800s in our Irish genealogy research.  The lack of paper records makes finding that connection to Irish royalty challenging.

   DNA is the next best answer to the lack of records.  Both regional and surname projects can collect enough genetic samples to build family trees.  Not in the same sense as child - father - grandfather etc., more in a phylogenetic sense.  A phylogenetic tree will show how individuals connect back to common ancestors and in turn, those common ancestors trace further back to another common connection.

   I have McCarthy ancestry and like everyone else I have researched as much as possible about one of my surnames.  Historically the surname comes from Carthaigh or Carthach, an 11th century King of Ireland and ancestor of the McCarthy Kings of Desmond (current day Cork and Kerry).  His son, Muireadhach, was the first to take on the Mac Carthaigh name.  Literally the ‘son of Carthaigh’.  In names like O’Neill or O’Brien, the O’ means grandson or descendant.

   Time to go for the gold.  How am I related to the Kings of Ireland?  Which DNA haplogroup do the McCarthys belong?  First, I found that a surname project existed on Family Tree DNA.  Then I started analyzing the data on the McCarthy Surname Study DNA site.  Nothing is ever simple.  There are six different haplogroup represented in the group, E1b, I1, I2a, I2b, R1a and R1b.  There are also four different R1b subgroups.  The site has R1b divided into Group A (SNP R-L21), Group B (SNP R-P314.2), Group C (SNP R-M222) and Group D (misc. others).  I would expect there to be multiple R1b subgroups as it is the most numerous haplogroup in Western Europe.

   Like the Olympics, there can only be one gold medal winner in this event.  Only one (or none) of these groups can be related to the original Carthaigh.  There are many reasons why there are multiple McCarthy haplogroups.  The Administrator of the McCarthy site, Nigel McCarthy, is well aware that there could be non-paternal events and has posted some possible situations where a McCarthy name could have arisen:

“•Soldiers, serfs, or slaves or hostages taken in battle and who remained with their captives, all under the tutelage of a McCarthy king, chief of chieftain, adopting this surname.
•Rape of McCarthy womenfolk by invading forces.
•Other illegitimacy.
•Adoption (e.g. by a chieftain of a sister’s orphaned children).
•Raiders such as Vikings being absorbed, a century or two after they settled in Ireland,  into the group which became the McCarthy family as they became “gaelicised”.
•Stepsons taking the McCarthy name of their new stepfather (early deaths of husbands or wives, and thus remarriages, were common).
•The sons of Cárthachs other than he who died in 1045 forming their surnames in a similar manner (although there is no explicit evidence of this).”
-source McCarthy Surname Study - Background

   Which genes are the royal McCarthy genes?  Other projects have been able to analyze DNA records and come back with an announcement that they have identified the haplotypes of Genghis Khan or Niall, ancestor of the O’Neill kings.  The same methods should work for the McCarthys.  If we consider the McCarthy DNA records as a random sample representing the larger population, then the groups with the larger number of records are more likely to be part of the royal group.  A wealthier family would have had more resources to provide for larger families, allowing for more descendants.

   Looking at the McCarthy site, haplogroup R1b Groups A and B have the most records.  At first glance, the other haplogroups seem to be ruled out for lack of representation.  An analysis of the haplotypes within these haplogroups gives us additional evidence.  The E1b group shows a clear pattern of migration from Greece through Italy, Germany, England and Scotland before arriving in Ireland.  This is consistent with the Alexandrian origin of E1b and the timing fits with Rome’s incursion into the region.

   Haplogroup I2b shows a migration from the Danube River region through Germany, England, Scotland and into Northern Ireland.  They appear to have arrived before the Romans.  Haplogroup R1a originated from Eastern Europe and took a different path via Normandy, Devon/Cornwall, into Ireland through Cork.  Their timing fits the Norman invasion of Ireland about 900 years ago.

   If we calculate the time to most recent common ancestor (TMRCA) for Groups A and B, we see that within each group they are closely related.  For each group, their common ancestor lived about 1,000 years ago, which coincides with Carthaigh’s timeframe.  Comparing the two groups against each other shows a common ancestor over 2,800 years ago.  Both groups have the right ancestral timing.  Group A has DNA that is associated with Southern Ireland and an analysis across a larger R1b tribal haplotype indicates that this group entered Ireland over 2,600 years ago.  The same analysis of Group B indicates that they entered Ireland about 500 years later.  Group A has been in Ireland longer and occupy the ancestral region of Desmond.

   So far, we have circumstantial evidence.  We need something more concrete.  We can get a clue from the historic royal genealogies.  The McCarthys were more than just a royal family.  They were a dynasty.  Along with the surname McCarthy, there were also the Sullivans, Callaghans, Keeffes, Donoghues and Donovans that made up the larger related genetic dynasty.  Looking at each group in the context of the larger genetic pool of records and surnames shows that Group A has a close DNA connection to the dynastic surnames and Group B does not.  This method was a key factor in the O’Neill project.

   The evidence points to Group A as the descendants of the royal McCarthys.  The haplotype for Carthaigh is slightly different from the modal for the McCarthy Project Group A.  Considering the dynastic records, makes the values of DYS576=19 and DYS442=13.

   The pedigree of Carthaigh’s ancestors borders on mythology.  Many Irish pedigrees trace back to Milesius of Spain as the father of the Irish people.  Historians found it easy to dispute these claims as these records often are full of conflicting historical information, a lack of dates and obvious attempts to connect back to the Biblical genealogies.  As with most mythology, the Irish origins contain grains of truth.  Haplogroup R1b, which is predominant in Ireland, has its origins in Iberia (modern day Spain and Portugal).  The McCarthy Group A DNA data can be traced backward in time via STR mutations to their Spanish and Portuguese cousins.  Imagine two brothers at a farewell party on the slopes of the Pyrenees 3,000 years ago.  One brother has decided to go north to seek better fortunes and the other decided to stay behind.  The ancestors of each exist today for us to compare.

   The Irish do have ‘Spanish’ origins.  Some elements of that oral history remained intact over 3,000 years as the Iberian tribe migrated and settled in Ireland.  As with any oral tradition, embellishment can occur, especially when developing a royal pedigree to show divine right.

   McCarthy Group A was not the first Iberian tribe to land in Ireland and certainly not the last.  Group B arrived about 500-1,000 after Group A.  Irish mythology suggests that there were at least four previous waves of immigration to Ireland from the mainland.  The E1b McCarthy ancestors begin to show up around 2,000 years ago with the Roman invasion and the R1a McCarthys are associated with the Norman invasion of Ireland about 900 years ago.

   My next steps are to find my male McCarthy cousins and get them tested.  I’ll look for at least two, one from each of my g-granduncle’s surviving lines.  My McCarthys trace back to Kilmichael Parish in County Cork and my gg-grandfather, Florence McCarthy, has one of those names that repeats throughout McCarthy history.   I look forward to finding out which McCarthy DNA group I belong.

   If you are a McCarthy, please consider DNA testing and joining the McCarthy DNA Project.  Your data will help build a better understanding and a better genetic family tree of the McCarthy groups.  Along the way, we can learn more about our ethnicity and our Irish culture.  You may even want to change your surname back to its original Irish spelling, Súilleabháin (Sullivan), Ceallacháin (Callaghan), Donnchadha (Donoghue), Donnabhain (Donovan) or Mac Carthaigh.

© Origin Hunters & OriginsDNA


  1. I have been surfing online more than 2 hours today, yet I never found any interesting article like yours.It is pretty worth enough for me. Personally, if all site owners and bloggers made good content as you did, the web will be much more useful than ever before.
    Feel free to surf my website genealogy in ireland

  2. thanks, a lot of good information. do you know how close are the Galician's of north/west Spain to the Galician's of west Ukraine? and how certain can you tell the years apart in each group and the roots they migrated through?
    Galilee (north kingdom of Israel)
    Gaels (Scottish,Irish)
    Galician's(Carpathian mountains Ukraine-Poland)
    Galatian's (Turkey)
    Gaul's (France)
    Gaulantis (North Israel)
    although not all of these people still exist today because invading empires it would be interesting to try and link there common ancestry and show the similarities in the living ancestors in the various parts of Europe.
    it is un doubtable that these people descend from the people of northern Israel who fled from the Assyrians.

    Iberi means descendant of Abraham (Hebrew in English), Iberia land of the Hebrew. Tiberias (northern Israel at the sea of Galilee). Hibernia (Ireland) Hebrides (Scottish Gaelic islands). this word is still used by "jews" today who claim this same ancestry also but that is far more arguable than this.

  3. Very interesting! I'm an O'Brien, with the surname being the 5th most common in Ireland, not all O'Brien's descend from Brian Boru. Some ten years ago the 'Irish Type III DNA' was discovered and found unique to the area of ancient Thomond, or north Munster province in Ireland. If one has the unique markers of this group then one's ancestors were of Brian Boru's tribe, no matter the surname, but especially for the name O'Brien.

  4. Michael,

    Please consider updating your conclusion on the origins of the McCarthy kings of Desmond and Cashel based on evidence presented under "Summary of Findings" at

    Have you yet found any male McCarthy relations to represent your own family in the Y-DNA study?

    Nigel McCarthy

  5. Interesting discussion. We can trace McCarthy ancestors back to Cork.


Relaunching Origin Hunters

   For the past four years I haven't been very active writing or attending genealogical conferences.  My focus has been quietly he...