Monday, 15 August 2016

Lineage II: our Nearest Neighbours - why are we related to them?

In the previous post we identified the nearest neighbours of the Lineage II Gleeson's from North Tipperary. In this post we explore why we might be related to them and how.

Our closest neighbours genetically are four people called Carroll. Next to them are a Prendergast, a Phelps, two McCarthy's, four McMahon's, a Bell, and an O'Keefe. Further back, we have a connection to another McCarthy and a host of other surnames including: Creamer, Miller, Treacy, Bowman, Nicholson, McConnell, & Mack. Somewhere in the mix there may be an Orgain and a Morrison, but their exact relationship to the others is not well-defined. And finally there is a list of additional surnames some or all or none of which may be related to the Gleeson's at some stage in the last few thousand years.

Note that the red dashed line in the diagram below indicates that the individual sits at or somewhere below the SNP indicated. See this Glossary (to follow) for abbreviations used in the text.

Lineage II Gleeson Neighbours - output from the analysis described in the previous post
Border indicates source: blue Nigel, grey Z255, green L21, red Ireland Y-DNA

Why might any of these surnames be related?

There are several possible explanations for the genetic connection between any two of these various surnames:
  • Pre-surname connection i.e. both spring from a common ancestor pre-surnames (i.e before 1000 AD approximately for Irish surnames)
  • Ancient NPE (surname switch)  e.g. a McMahon family swore allegiance to the ruling McCarthy's and adopted their surname. Thus McMahon DNA was passed down with the McCarthy surname in subsequent generations
  • Recent NPE (DNA switch)  e.g. we saw in a recent post how the Phelps connection may be the result of a secret adoption of a Gleeson/Carroll/similar child sometime around the 1670s
  • Convergence - i.e. because of Back & Parallel Mutations, two surnames look more closely related than they actually are and the connection is 5000 years ago, not 1000 years ago. This is more likely to be a problem with those surnames that were generated from the Matches Surname Analysis (orange box to the right in the diagram above).

Our genetic neighbours could be related in any number of different ways

Is it possible to distinguish between the various possible reasons for the genetic connection?

There are several techniques that can be used to explore this question and the output can increase the likelihood of one explanation over another.

If you know how old a particular group of people is, this can help place their emergence on the Human Evolutionary Tree. TMRCA estimates using STR data are a helpful starting point, but are probably too crude to date the age of a group before 1000 AD. When dating the emergence of a particular group prior to 1000 AD, TMRCA estimates using SNP data are a lot more accurate than STR-based TMRCA estimates. Using these techniques we might be able to determine the likelihood of which came first - the (Gleeson) chicken or the (Carroll) egg. 

However, it should be borne in mind that the TMRCA estimates the branching point between two people/groups - the emergence of the defining SNP may be several hundreds of years before that. Thus the placement of a group on the Haplotree may be further back than the data might suggest. In other words, SNP-based TMRCA estimates may place a group at a later timepoint on the Haplotree than when it (and the defining SNP marker) actually first emerged.

A recent NPE is more likely when there is only a single occurrence of that particular surname with that particular genetic signature within the database, and most of the other people who bear that surname have a different signature. A recent NPE may also be more likely if the GD Spread within a group is small, indicating an MRCA within the last few hundred years.

The most difficult situation is trying to distinguish an ancient NPE from a pre-surname match. And this is where historical evidence (e.g. from the Ancient Irish Annals) may be of some help. Is it more likely or less likely that a particular surname would be subject to a surname switch or a DNA switch?

For example, the Gleeson's were never the most powerful Lords in the Kingdom. The Kennedy's and the O'Brien's were the important chiefs. Thus it would be perhaps more common for other families to adopt the Kennedy name as a mark of allegiance ... which from the Kennedy point of view results in a DNA switch (i.e. same surname, different DNA), and from the Gleeson point of view results in a surname switch (i.e. same DNA, different surname). In this case, one man's surname switch is another man's DNA switch.  Extrapolating from this, it would be more likely that the Kennedy and O'Brien surnames would be characterised by a host of different genetic signatures. 

The corollary of this is that families more lower down on the social scale would tend to not have a diverse range of genetic signatures associated with them, because there would have been no tendency for other families to swear allegiance to them. Thus the Gleeson's may have kept their surname relatively genetically intact compared to the more powerful Kennedy's.

However there may be other forces acting in the opposite direction. There was no concept of illegitimacy or infidelity under Brehon Law ... apparently. If this indeed was the case, then there could have been an awful lot of DNA flying around. Perhaps the more powerful men were in a better position to do this (they had the means to support concubines and had ready access to servants). This could mean that the DNA of powerful people (e.g. the Kennedy's) is more likely to emerge under the guise of different surnames than perhaps Gleeson DNA.  In other words, the Gleeson's may have been more inclined to keep their DNA to themselves. And as a result we might find that some Gleeson's will carry the DNA of important families (the Kennedy's and O'Brien's were Dal Cassian so we should expect the SNP L226 to feature among us, as indeed is the case with Gleeson Lineage III). 

So, as far as the Gleeson surname is concerned, some forces pull us in the direction of having relatively few genetic signatures associated with the name (e.g. we were not a powerful dynasty), and other forces (e.g. ancient shenanigans by the chief) pull us in the opposite direction.

If there is an ancient NPE somewhere between the Lineage II Gleeson's and their neighbours, then there is a relatively limited gene pool from which it may have arisen. Below is a map of the main families in the area of North Tipperary towards the end of the era of the Gaelic Clan System. Based purely on proximity, it is among these names that we would have higher expectations of stumbling upon the source of any NPE.

from The History of the Ely O'Carroll Territory or Ancient Ormond by Rev. John Gleeson 

Based on the above, there are certain questions we can ask when examining the evidence for each genetic neighbour:
  1. Does it look like a recent NPE?
  2. Where did the person/group come from? Is there a specific ancestral location identified?
  3. How old is the group? Can we determine when it branched off from the main trunk of the Haplotree? and if so, where does this place it in relation to the estimated branching points of other related surnames?
  4. Do Surname Dictionaries give us any clues to the surnames origin? 
  5. Did any of the related surnames exist in close proximity to each other?
  6. Is there any historical evidence (from recent history or the Ancient Irish Annals) of a relationship between any related surnames?
Let's look at each of our supposed genetic neighbours in turn. I'll deal with the recent NPEs first as these are easier to identify.


We have already explored how this is probably a recent NPE. Thomas Phelps was a Cromwellian soldier from Gloucestershire who was granted land right in the heart of Gleeson territory. The evidence suggests that somehow "local DNA" became associated with the Phelps surname, probably sometime around the 1670s, and subsequent descendants carried this to America, including Maryland and North Carolina. See this previous post for the full account.


Interestingly, Bell does not even show up among the STR matches of any of the Lineage II project members. This indicates that his genetic distance from the Gleeson's is below the threshold for declaration at every level of comparison (from 111 markers down to 25 markers). 

However, I have received information that this particular individual does not have any close matches among the 486 other Bell's in the Bell DNA Project (thus suggesting this may be a recent NPE). Furthermore, his MDKA is a Percy Bell, born before 1912 in New Orleans, Louisiana, who was apparently African American. This information suggests an NPE occurring somewhere in America during the time of slavery on this person's direct male line, with a Gleeson or a Gleeson neighbour as the genetic ancestor.


Similarly to Bell above, this Prendergast individual does not show up as a match to anyone in Lineage II. His terminal SNP is Z16443 (Haplogroup R1b) and the TMRCA to the Lineage II Gleeson's is about 170 AD (via Susan Hedeen's calculations - see the Z255 Yahoo group).

He does appear however in the Z255 Project which reveals that his MDKA was born in Maine in 1849. In the Prendergast DNA Project, he sits in a separate group on his own, and has no close genetic matches (all of which suggests an NPE).

MacLysaght (1985) reports that Prendergast is a Hiberno-Norman name and first came to Ireland in the 12th century with the Norman Knight Maurice de Prendergast, a contemporary of Strongbow. A branch of the family established itself in Newcastle, Co. Tipperary but their lands were subjected to the post-Cromwellian confiscations of the mid-1600s. Some lands were retained, however, and their holdings in Tipperary included Ardfinnan Castle. This places the Prendergast name in roughly the right place for an NPE to occur.

The Prendergast DNA Project and Haplogroup R1a Project have reasonably-well characterised the SNP markers for the Prendergast's with YP543 and it's downstream SNPs (YP4467, YP544, & YP541) being exclusive to the Prendergast surname (i.e. so far, they do not occur in association with any other surnames). All of these SNP markers belong to Haplogroup R1a, a completely different Haplogroup subclade to our Prendergast's Haplogroup R1b. 

Extract from the Haplogroup R1a Project

The earliest of these Prendergast-specific SNPs emerged sometime between 550 and 850 AD, and the most recent one emerged about 1625.  So this currently places the Prendergast common ancestor on the Haplotree somewhere between 550-850 AD, indicating that the roots of this lineage are very old.

The balance of the evidence suggests that DNA from a "Gleeson or neighbour" entered the Prendergast line and was passed on to subsequent generations. This could have happened relatively early on (say between 1200-1600) given that the TMRCA with the Lineage II Gleeson's is 170 AD.

Dates of emergence of Prendergast-specific SNPs
(from the YFULL Haplotree)


Four Carroll individuals were identified from the previous analysis. These all belong to group "R-L21, Z255, Z16437" in the Carroll DNA Project. This particular group has 16 members suggesting that this is not a "chance signal" (e.g. recent NPE) but rather quite a substantial one.

Is there any indication of a specific ancestral location?
Of the members with declared Irish origins, 3 are from Tipperary, one from Kilkenny.  This certainly places some of them "in the right place", given that the Lineage II Gleeson's are from North Tipperary.

The relevant Carroll group from the Carroll DNA Project

How old is this group?
There appears to be quite a degree of GD Spread in this group, with the maximum Genetic Distance between any two members being in the region of 18/37. This suggests that this is a very old group with a common ancestor that goes back to perhaps some time before the 1300's. This in turn suggests that there is no NPE in this group since this time. It is not possible to get a specific STR-based TMRCA  estimate for this group without access to the data so in this situation it is necessary to write to the Project Administrator and ask him/her for the information. 

It would be useful to perform Big Y tests on the most distantly related members of this group so that we could maximise the chances of identifying the defining SNP for this particular group, and so that we could get another age estimate for the MRCA using SNP data (in addition to the STR-based estimate used above).

Interestingly, the MSA (Matches Surname Analysis) for Lineage II revealed a low maximum mpm (matches per member) value of 0.3 (at 37 markers). This could happen with a very distant connection (e.g. pre-surnames, for example). In other words, one would expect the signal of a genetic connection to be diluted and eventually lost over time as the two groups diverge from each other with progressive STR mutations. This is why SNP evidence is more informative when trying to detect a distant connection between two surnames.

What is the origin of this surname?
The Carroll DNA Project quotes Woulfe (1923) as describing six possible Carroll origins. Of relevance to our story ...
  • the Ely O'Carroll were originally Lords of Eile which comprised the baronies of Ballybritt, Clonlisk, Ikerrin, & Eliogarty ... in other words, just east of the Gleeson stronghold of Upper Ormond (see map above). This is in effect "next door" to the Lineage II Gleeson's. 
    • The Project Admins suggest they have identified the most likely genetic signature for this group, namely R-L21, DF21, 492=11, the Ely Carroll modal category. 
    • They say: In September 2011, the Carroll project announced that "so far no one has come forward who can trace their Carroll roots back to the 1500's except of course the participant Member Kit Number 112378 who is a close relative of the family of Charles Carroll the Signer." Of Carrolls who have tested 67 or 111 markers, 15% are in this Ely Carroll category.
    • This is a completely different category to the one to which the Lineage II Gleeson's belong.
  • the O'Carroll's of Oriel (Airgialla) were of the same stock as the McMahon's (close genetic neighbours to Lineage II) but they hailed from the Kingdom of Oriel which is a bit too far away (around modern Armagh & Monaghan). So unless there was a mass migration it seems unlikely that we would be related to this particular group. Perhaps these are a different set of McMahon's too ...
    • The Project identifies a possible genetic signature for this group, namely: R-L21, DF21, 511=9, 425=0, 505=9, the Clan Colla modal category. 
    • They note: In September 2009, the Carroll project announced that a group of participants "may be related to the O'Carroll Princes of Oriel (Monaghan and Louth). This Kingdom located in the North of Ireland was founded by the three Collas Brothers around the year 327 AD." Of Carrolls who have tested 67 or 111 markers, 23% are in this Clan Colla category.
    • This is also a completely different category genetically to the Lineage II Gleeson's.
  • the O'Carroll's of Ossory (Osraige) came from modern day Kilkenny, still within the province of Munster but east of Tipperary (near present-day Kilkenny).
    • they are potentially identified by R-P312, DF27, Y5058, A641, 390=25, 481=24, 520=21, CDYa=33, the Breassal Breac category. Again, this is a different category to the Lineage II Gleeson's.
Modern Irish Map compared to maps of the Ancient Gaelic Kingdoms

So there is no apparent genetic connection or genetic consistency between the Lineage II Gleeson's and any of the above O'Carroll categories. And this despite the Ely O'Carroll group and the Ossory O'Carroll group being practically next door neighbours. The closeness seems to be crying out for some sort of an association. Possibly an NPE? Did some Gleeson's switch their surname to Carroll as a sign of allegiance to their neighbouring chiefs?

However ... Woulfe could be wrong in his categorisation of the O'Carroll clan origins; there could be other Carroll septs that have not been identified so far; the Carroll DNA Project could be incorrect in associating certain haplotypes with specific O'Carroll septs / clans; there may be other reasons for the lack of similarity that we haven't thought of ... yet. If you have any suggestions, leave a comment below!


According to  the McMahon DNA Project website, there were two main groups of McMahon's - the MacMahons of Oriel in the north of Ireland (around Co. Monaghan), and the MacMahons of Thomond in the south (around Co. Clare). Thomond is right beside the North Tipp Gleesons.

Woulfe gives this information about the surname:
Mac MATHGHAMHNA—IV—M'Mahowna, M'Maghowney, M'Maghone, M'Machan, MacMaghone, MacMaghon, MacMaghen, MacMachon, MacMahon, MacMahan, MacMann, Mahony, Mahon, (Matthews, Mathews); 'son of Mathghamhain' (bear). There are two great Irish families of this name, viz.: the MacMahons of Thomond, and the MacMahons of Oriel. The MacMahons of Thomond are a branch of the O'Briens, and derive their name and descent from Mahon, son of Murtagh More O'Brien, King of Ireland (1094-1119). Their patrimony was Corca Bhaiscinn, which comprised the baronies of Moyarta and Clonderlaw in the south-west of Co. Clare ... 
The MacMahons of Oriel were formerly one of the most powerful families in Ulster. On the decline of the O'Carrolls in the 13th century, they became lords of Oriel, a rank which they retained down to the reign of Elizabeth; and even as late as the Cromwellian wars, they had considerable possessions and power in Co. Monaghan. 

The McMahon DNA Project has a group of 16 McMahons that are all closely related, two of whom have tested positive for Z16438 and two positive for the next downstream branch Z16435/6. It is therefore likely that all McMahon's in this group would test positive for Z16435/6. The group is currently split in two but the modal haplotypes for each group (C3.1 and C3.2) are very close to each other (GD approximately 2/37) and so I would consider these as all belonging to the same group.

The GD spread within the group is about 10/37 suggesting a midpoint TMRCA maybe some time in the 1300s-1400s. So this is an old well-established group and not a recent NPE.

Irish counties included among the ancestral locations for group members include: Galway, Limerick (x3), Clare (x2), & Kerry. This is in keeping with the traditional location of the McMahon's of Thomond.

The McMahon neighbours of Lineage II
(click to enlarge)
The question is: does the connection with Lineage II represent a pre-surname connection (i.e. via a common ancestor, as might be documented in the Ancient Annals) or an ancient NPE (involving a surname switch or DNA switch or both)?

Is there any evidence that the McMahon's and the Gleeson's were "of the same stock"?

So, what are the possibilities:
  • It is interesting that the O'Carroll name occurs in relation to the McMahon's of Oriel, given that an association between the North Tipp Gleeson's and the Ely O'Carroll or Ossory O'Carroll groups has been postulated. But is this an important finding or a coincidence? Is it a hot lead or a red herring? The fact that Oriel is so far removed from Tipperary makes me think this is more likely to be a red herring ... unless there was a mass migration from Oriel to Tipperary.
  • Group members have ancestral locations in Clare & Limerick primarily, in keeping with the Thomond McMahon's.
  • If the Thomond McMahon's were a branch of the O'Brien's, they should test positive for L226. Only one member does. 
  • If they shared a common ancestor with the Lineage II Gleeson's, the Gleeson's should bear L226 also. They do not.
  • So that leaves the following as possibilities:
    • The Gleeson's and McMahon's do share a common ancestor but it is not recorded in the annals.
    • An ancient NPE occurred and either a) genetic Gleeson's became McMahon's by name, or b) genetic McMahon's became Gleeson's by name.

It is conceivable that because the McMahon's were a powerful sept, that the Gleeson's swore allegiance to them and changed their name accordingly (i.e. surname switch from Gleeson to McMahon). There is little to suggest that the Gleeson's were ever war-like enough to command allegiance from other septs ... although a motto of "the strong hand will be uppermost" does give one some pause for thought.

An alternative scenario could have been that a Gleeson and a McMahon switched surnames independently to "Carroll" ... so the Carroll's ended up with both Gleeson and McMahon DNA associated with their surname.


Here is what Woulfe says about the McCarthy surname:
Mac CÁRTHAIGH—IV—M'Carhig, M'Carhie, MacCarha, MacCarthy, MacCartie, MacCarty, MacArthy, &c.; 'son of Cárthach' (Old Celtic Caratacos, loving, an ancient Irish personal name). The MacCarthys were the chief family of the Eoghanacht, i.e., the descendants of Eoghan Mor, son of Oilioll Olum, King of Munster in the 3rd century. They took their name from Cárthach, lord of the Eoghanacht, whose tragic death, in 1045, is recorded in the Annals. Cártach was the son of Saerbhreathach (a name still in use in the family, anglicised Justin), who was the grandson of Ceaillachán of Cashel, King of Munster in the Danish period. Prior to the Anglo-Norman invasion, the MacCarthys were Kings of Desmond, or South Munster; but shortly after that event they were driven from the plains of Tipperary into the present counties of Cork and Kerry, where, however, they became very numerous and retained considerable possessions down to the revolution of 1688. They were divided into three great branches, the heads of which were known respectively as MacCarthy More who resided chiefly in Kerry, MacCarthy Reagh, lord of Carbery in West Cork, and MacCarthy of Muskerry; and there were numerous minor branches.

The McCarthy men who match the Lineage II Gleeson's are a group only four people in McCarthy group E1. Two of the members hail from Cork & Kerry respectively, in keeping with what Woulfe writes about their ancestral locations.

Interestingly, one is positive for Z16435 and two for FGC39568, a SNP on the adjacent branch. The time to their common ancestor is about 120 AD, which is very far back indeed. Perhaps as more people test this group will break into two? ... just a thought that crosses my mind.

Also, a group of four is quite a small group. This raises the (low) possibility of a relatively recent NPE (within the last 500 years).

Furthermore, the Project Admin (Nigel McCarthy) identifies Creamer as a McCarthy in disguise. Here is what he writes:
... a West Cork McCarthy family - known to the writer - which took Cremane as an agnomen in due course became the Creamer family following migration to London, with no hint any longer of its McCarthy origins. Similarly some nineteenth century baptism and marriage records refer, for example, to the surnames Farshing, Crimeen and Meenig, but it is often clear from research that these are McCarthys.

Group E1 from the McCarthy DNA Study

So which came first? Possibly the McCarthy's if the TMRCA estimate of 120 AD is to be believed.

There is nothing to suggest that the McCarthy's and Gleeson's were descended "from the same stock" so a pre-surname connection seems unlikely.

Thus we are once again left with the idea that perhaps Gleeson's changed their name to McCarthy out of allegiance ... but this would not have happened around 120 AD ... so our picture here is incomplete. We need more data to draw more robust conclusions.


This name was one of the many surname offshoots of the Eoghanacht McCarthy sept in the south of Ireland.


Another name that comes up as a recurrent match among Lineage II members is McCloughan.  The similarity between the name McLachlan and McCloughan seems like an extraordinary co-incidence. Or is it? Could they both be derived from the surname Moloughney, a supposed Muskerry surname associated with the Gleeson surname? or is this a red herring?


The data is fragmented and is drawn from a variety of different sources. Having it collated in one place might aid interpretation (for example, they should all join the Z255 haplogroup Project and the Munster irish Geographic Project).

The DNA evidence suggests a close association between the Gleeson's of Lineage II and a variety of neighbouring surnames, some of quite powerful septs. Phelps and Bell are highly likely to be recent NPEs; Prendergast also.

But the association with other surnames is less clear. There is little evidence of a pre-surname connection for the association with the Carroll's and the McMahon's, and the possibility of an ancient NPE seems a more plausible explanation.

The McCarthy association is the most difficult to decipher. The small numbers in the Group E (four only) and the presence of markers on adjacent branches of the haplotree is difficult to explain.

More accurate TMRCA estimates and timing of SNP emergence/formation would help.

This topic will be one of ongoing enquiry so this post will be updated periodically as more data becomes available (and is absorbed and digested).

Maurice Gleeson
August 2016

1 comment:

  1. Maurice, this is fascinating, thank you very much!