McCaffrey DNA Project Discussion








        We are fortunate to have achieved some early success with the McCaffrey DNA Project. To date, we have the yDNA profiles for twenty-two members and the short lineages for fourteen. In our experience, this is a better than average start for a yDNA project.

        We have already achieved one of our initial goals. We wanted to prove that some modern day variations of the McCaffrey name are related. Specifically, we have proof that a McCaffrey, a McCaffree, a McCafferty and a Caffrey have a Common Ancestor (CA). These facts should serve as a wake-up call to those who overemphasize the importance of surname spellings in their research efforts. It should also encourage those with variant spellings to join the project.

        However, we have encountered an impediment to our progress. Apparently, in the early days of yDNA testing at FTDNA, Several McCaffrey, etc. men had their yDNA tested; however, because a McCaffrey DNA project did not exist and they probably did not get many or any matches, they seemed to have lost interest. This situation has resulted in three important FTDNA yDNA matches, however, we only know a few details about these people. We have tried to email two of these these folks, but these attempts have been unsuccessful; some bounced and some have gone unanswered, indicating that these addresses are probably not being used for some reason. Privacy policies at FTDNA do not allow them to provide any other information. We need these people to join our project or contact us. This action could lead to significant lineage connections and lineage extensions.  Therefore, we are going to list what we know about these mystery folks in hopes that a reader will recognize a name and assist us in some way.

John Edward McCaffrey, GD= 2 w/ kit # 486944
James McCaffrey GD=3 w/ kit # 319977
? McCafferty, no email, Most distant ancestor is Hugh McCafferty GD=1 w/ kit # 346400 & GD=2 w/ kit # 250346

        The Genetic Distance (GD) between two yDNA profiles is the number of marker (DYS#) differences found when the two profiles are compared. In general, for 37 marker profiles of the same/similar surnames, a GD of 0 to 5 is considered a match and for 67 markers, a GD of 0 to 7 is considered a match; however, these conventions are based on the observed average mutation frequencies of all surnames. There are a small number of surnames that fall on both sides of this average, sometimes significantly so. That is, some surnames have mutation rates well above that average and some have rates well below the average; therefore, the GDs of the these exceptions may have different interpretations than those for the general population (average). For the general population, smaller GDs usually indicate closer relationships; however, as demonstrated by Group 3, this is not always so. Group 3 includes at least three individuals with GDs=0/1 that are at least 5th cousins and are descendants of a McCaffrey born at lesast 250 years ago. This is a small sample, but implies a mutation rate of approximately one per two hundred fifty years and when extrapolated, four per one thousand years.
        Our project success and some of our participants yDNA genetic profiles have encouraged us to do some additional historical research. First, it is helpful to know that when the genetic profiles of individuals with completely different surnames are compared, small GDs indicate the possibility of a Common Ancestor (CA). The smaller the GD, the greater the probability of such a connection. In addition to comparable GDs, the number of matches with comparable GDs is at least as important. That is, a large number of matches with comparable GDs with a dissimilar surname increases thes probability of a genetic connection between the two dissimilar surnames.  Group 3 members of the project have over thirty matches with individuals surnamed Maguire/Mcguire, some as close as GD=2@67 markers. Also, Group 4 members have about the same number of matches with individuals surnamed Doherty/O'Doherty and variations, some as close as GD=1@37 markers. Some insight into this phenomenon comes from Rev. Patrick Woulke in his 1923 
reference, Irish Names and Surnames. The Rev. Woulfe divides the surname origins into two "tribes". The first and most widely known was derived from Gadfraidh, the son of Donn Mor Maguire (1260 AD - 1302 AD). Over the years this name became Mac Gadfraidh, M'Gafferie, MacGaffrey, MacCaffray, MacCaffrey, MacCaffery, Caffrey, etc. Bearers of this surname were part of a sept (sub clan, division) of Clan Maguire which ruled the Fermanagh region from about 1250 AD to 1607 AD. The second tribe was derived from  Eachmharcach (horse rider), a given name often used by the O'Doherty Clan of Counties Donegal and Mayo. This name evolved into MacEachmharcaigh, M'Cafferchie, M'Cafferkie, MacCaffarky, MacCagherty, MacCaugherty, MacCafferty, MacCaverty, MacCaharty, MacCaherty, MacCarthy, MacCaffry, Cafferky, Cafferty, etc. Irish history provides abundant evidence of the Maguire/McCaffrey connection in Fermanagh. In fact, the McCaffrey, etc seat of power was established at this time in the small townland of Ballymacaffry in Fermanagh. Ballymacaffry still exists and is near the border of County Tyrone, just west of Fivemiletown and about 13 miles due east of the much larger town of Enniskillen. Enniskillen is the location of the Maguire Castle, a well known tourist destination constructed in the 1420s. The ancestors of both the Maguires and O'Dohertys have been recorded by Irish historians well before the end of the first millennium. This research has led us to another interesting fact: In the earliest Irish records, related families used the MacCaffrey, McCaffrey, McCaffery, McCafferty, Caffrey and similar variations. Since Caffrey was a McCaffrey variation used in Ireland, it surely existed in other places. so we have added Caffrey, etc to our list of potential project participants.

Created Jun 7, 2016
Revised Jun 11, 2018