1.  Study Members

2.  Branches using the Irwin Surname (or variants thereof)

3.  Comments on individual branches, including L555 genetic family tree

The following analyses are taken from the Main Results Table (see Latest Results Tables) as of end April 2024.  These analyses will be next updated in November 2024.

Note:  The terms STRs, SNPs and haplotrees are introduced in "Interpreting yDNA Test Results".

1.  Study Members

The Clan Irwin Surname DNA Study includes testers from the Erwin, Genographic and Irish Heritage projects, and testers with other surnames who appear to be close yDNA matches. It also includes a few testers with yDNA test results obtained from companies other than FTDNA.  It does not include those who have taken autosomal or mitochondrial tests but have not taken a yDNA test.  

As of end October 2023 our Study has 620 members with yDNA test results.  This total is less than the 714 members of the Irwin Clan Surname Project shown for the FTDNA Irwin Clan Surname DNA Project because the latter includes kits that have not been returned, kits undergoing initial analysis, and some testers who have taken atDNA or mtDNA tests but no yDNA test.

Details of members’ year of joining and country of residence are:                                                       

Year No.

2002-5 25

2006 45

2007 36

2008 42

2009 27

2010 30

2011 40

2012 41

2013 32

2014 41

2015 24

2016 40

2017 37

2018 20

2019 29

2020 33

2021 36

2022         20

2023 15

2023 to date 12

Residence %

USA 69

Canada   6

Australia   6

Scotland                          5

England & Wales            4

Ireland   2

New Zealand   1

France   0.3

Unknown                         7

To place these figures in context, the members of our Study represent about 0.2% of all Irwin men alive in the world today.  81% of our members reside in the New World, while 82% of the total population of Irwins etc. live there (see Supplementary Paper No.1 and Supplementary Paper No.2).  But while these comparisons show a good correlation between our members and the global Irwin population in the geographical context, this is not necessarily so in the socio-economic context, where the expense of DNA testing will have deterred many less affluent Irwins from taking a DNA test 

Members have volunteered the name, date of birth and place of origin of their earliest confirmed paternal ancestor:

Irwin members

The “Other” spellings are members with surnames unlike Irwin but whose DNA indicates their ancestors were genetically related to a branch of the Irwin surname (see below).

Some members have given more specific details about their earliest confirmed paternal ancestor, or where their ancestors first settled after migrating, from which the following was derived in 2016: 

Ancestor settlement

These distributions can be interpreted as representative of a general trend of migration from the Scottish Borders to Ulster during the 17th century, and of migration from Ulster to Colonial America during the 18th century.

The types of STR tests taken by members breaks down thus:

No. of STR markers tested % participants

12 or less   4

25   0.5

37 47.5

67 13.5

111 12.5

>111 22

i.e. 95.5% of our members have tested to 37 markers of more.

The 37 marker test has proved the most popular and cost effective.  Lower resolution tests, i.e. with less than 37 markers, have been found to be inadequate for most members.  The 67-marker Test (no longer available) and 111-marker test have yielded little additional benefits, and the new Panels 6 and 7 (markers 112-838) which now accompany the BigY700 tests also have little value. 

Upgrading to 37 markers is recommended for all testers with less than 37 markers. Upgrading to 111 markers is not recommended without prior consultation with the Study Administrator.  For members of our Borders branch (see below) who have not taken a BigY test, the new BigY700 test would be a much better investment.  Financial assistance may be available, especially to members of the Clan Irwin Association. 

137 (22%) of members have BigY test results, of which 127 (20%) are BigY700.  A further 55 (9%) have SNP Pack test results.   60% of Border Irwins can now be placed on the L555 genetic family tree (see section 3.1 below). 

SNP tests and FTDNA's haplogroup predictions based on STR data show the 613 testers to be members of the following haplogroups: 

Haplogroup:    R1b1 I1 I2 E J1 J2 G       R1a     C

Members:   89.4%   3.9% 3.0% 1.0% 1.3% 0.7% 0.3%      0.2%      0.2% 

2.  Branches using the Irwin Surname (and variants thereof) (including NPEs)

On the basis of STR data it has been possible to identify 47 branches (aka genetic families) using our surname that are each apparently unrelated to one another other during the surname era (i.e. roughly the last millennium):

Irwin branches

All but 8 of these branches have representatives living in North America today. 

Although these branches are unrelated during the surname era, all men are descended from a "genetic Adam", and the enormous haplotree of all his male descendants, continuously evolving, can be simplified to show only how members of these Clan Irwin branches are related to one another, thus:

The short "codes" in red and green shown in this table represent the branches (aka genetic families) indicated by similar codes in the Summary table immediately above and in our Main Results Table.  The dates and the Surname/Pre-surname threshold on the right only relate to the L555 ancestral line and are taken from FTDNA's "Discover" tool).  The purpose of this table is not an exercise in "deep ancestry", but simply to show that the 40+ branches of the Irwin surname are not related to one another within the surname era. 


3.  Comments of individual branches (including the Border Irwin genetic family tree)

General.  Each of the 48 branches of our surname that are now identified warrants its own analysis and discussion.  Below I discuss the Borders branch in considerable detail, in a way not possible with the smaller branches whose members between them have less than two BigY tests.  But for a growing number of smaller branches that do have two or more BigY tests (i.e. at present  O1, SM, ND, NG, I?L, IM, IR1, G, U4) I can make a more detailed analysis.  Such detailed analyses and discussions are not included below, but have been communicated direct with the few testers concerned.   

3.1   Borders branch.  This is thought to be the largest such branch in all the DNA surname studies. It includes nearly two thirds of all our members. All of the Study members included in this branch share a single paternal ancestor whose identity is unknown but who apparently lived in the Scottish Borders, probably Dumfriesshire, during the 14th century.  Although few genealogical records survive from this period, we know he lived there because a few members in this branch are still alive in Dumfriesshire today.  We know roughly when he lived from the absence of hereditary surnames of amongst low-ranking Scots in the 13th century, and some contemporary records of Irvings in Dumfriesshire in the 1370s.  Many of the Study members living in USA and who were previously unsure of their distant paternal ancestry are gratified this link to the Scottish Borders has now been established.  Most of these American members are probably “Scots-Irish”, i.e. they had an ancestor who migrated from Dumfriesshire to Ulster, typically in the 17th century, and a later ancestor who migrated from Ireland to USA, typically the eastern seaboard states from Pennsylvania to the Carolinas, and mostly in the 18th century.  Both these migrations were probably for reasons that were primarily economic, although some migrations to Ulster may have been by Border reivers fleeing the courts, and some migrations from Ulster may have been by Presbyterians seeking less discrimination.

Several members using surnames unlike Irwin are included in this branch as they evidently share this common ancestry, and so are NPE's (see section 2.6 of Interpreting yDNA Test Results). Armstrong, Beattie, Bell, Elliot, Fleming, Graham, Johnston, Little and Rutherford are all common Borders surnames, while Byers was a common name in Annan.  Errand is probably not a name change but a different surname.  The Cahill, Hamblen and Hutchinson members know their relevant recent ancestry included such events.  However all members with a surname unlike Irwin but whose STR signature matches than of the Border Irwins should take a L555 test (single or Pack Test) if they have not already done so, to confirm they are a NPE rather than a False Positive.

In early 2011 a tentative division of most of the members in the Borders branch into 14 sub-groups was attempted using cladograms and FTDNA's old TiP tool.  The modal DNA signatures of these sub-group were denoted thus: BA (modal), BB (Bonshaw), BD (Dumfries), BE (Eskdale), B9, B10, B15, B16, B17, B23, B29 and (for the "left overs") BX.  The background to these sub-divisions was addressed in Supplementary Paper No.3 ("Identifying Sub-groups ....").  This tentative division of our large Borders branch into these sub-groups represented a significant development at the time and served well for five years, even though it placed some known close cousins in different sub-groups.  With the arrival of BigY tests in 2015 we initially got one such test for each sub-group.  This development did not itself immediately confirm or disprove the reliability of these sub-groupings, but with the advent of the cheaper SNP Pack tests in spring 2016 it became apparent that most of these tentative sub-groupings were incompatible with the new and much more reliable SNP test results (see below).  Subsequent BigY tests have revealed a much more complex haplogroup than these tentative sub-groupings had been implying.  

The test results for the Border Irwins in the Main results table are thus now split into two categories: B(1), for those Border Irwins who can now be placed on the L555 haplotree, and B(2), for the remainder.  Members in B(2) can "graduate" to B(1) and be placed on the L555 haplotree by taking a BigY700 test (now down to $379 in FTDNA's periodic Sales ($319 if 37-marker test already taken).

Thanks to the investments of an increasing number of L555 members in BigY tests and Pack tests, and more recently in the BigY700 test, the L555 section of the Clan Irwin haplotree above can now be expanded downstream into what I have called a Genetic Family Tree, thus:

Click here to download the more legible Excel version.  If desired, this can be printed on a legible scale on six portrait sheets of A4/letter-size paper which can be selotaped together.  If you can't get a format that suits you, or you want a more up-to-date version the the six-monthly on-line version, please e-mail the Administrator!

Note that this genetic family tree is essentially the same as the haplotree presented in the B(1) section of the Main Results Table, but turned through 90 degrees and with the members sequenced in a different order: in the Main Results Table most members are sequenced as per the FTDNA haplotree;  in the L555 haplotree above some have been resequenced to improve the clarity, showing of the non-Irwin branches of L555 on the left and the Bonshaw SNPs on the right.  The column numbering in blue across the L555 haplotree are inserted in column "R" of the Main Results Table. 

The upper left portion of this haplotree shows the context of the L555 SNP.  The upper/middle right portion shows how the haplotree mirrors the early genealogy of the Bonshaw branch.  The bar chart shown bottom left quantifies the randomness of "young" / "downstream" SNPs , and shows why precise dating of these SNPs is so difficult.  The dates in italics associated with many SNPs are the mean dates currently estimated by FTDNA's new "Discover"/"Time Tree" tool.  The box bottom centre summarises specific conclusions that can be drawn for this data.  The box bottom rights summaries the data included in the tree.

The bottom third of this table attaches some members who have been added to relevant branches of the haplotree on the basis of STR predictions, Family Finder tests or previously known genealogical relationships, meaning that the expanded haplotree, which I have called a genetic family tree, now includes over 60% of all the members who are tested or predicted to be L555+ and can be placed on this tree. 

An abbreviated genealogy/pedigree of the Bonshaw, Castle Irvine and Killadeas lines is included on the right.  The "triangulations" of the SNP data for the representatives of the Bonshaw, Castle Irvine, Killadeas and other lines shown in bold font show the clear correlation between their pedigree and their relevant SNPs in the haplotree.  Very few other surname projects have been able to achieve such genetic confirmation of traditional pedigrees.  Alas the available pedigrees of the many other testers included in this haplotree and shown by a thick black line under the relevant TMRCA in bold) do not extend back in time far enough for them to be connected with the contemporary 14th-17th century records of the other Border Irwin branches that have been identified in Chapter 16.2 of The Irwin Surname: its Origins, Diaspora and Early Branches.  

Please note that details in this haplotree are liable to change as further tees results become available and interpretation and presentation are improved.  However already many interesting and important points emerge that relate to the Border Irwins: 

TMRCAs. In the main L555 tree above I have retained my manual calculations of the age of the FGC13746 block as these illustrate well the various parameters and uncertainties involved.  

However such manual calculations are now superseded by FTDNA's sophisticated "Discover More" tool which takes  into account the mutation rates of both SNPs and STRs.  The results of this tool change as its algorithms are refined and as more BigY test results become available.  The current estimated age of the youngest SNP in the FGC13746 block, which BigY tests suggest represents the earliest Border Irwin, is AD1325, with 68% Confidence Intervals of AD1252-AD1357.  It may be coincidental, but it is nevertheless gratifying that this estimate, and the two manual estimates accord so well with available documentary evidence. 

Note that FTDNA revise these TMRCAs from time to time.  

Kent Irvin has developed some very plausible correlations between these Bonshaw line SNPs and individuals on the Bonshaw pedigree, but I am refraining from “publishing” these until we have many more L555 Pack tests completed.   He and I have also developed pedigrees for the Irvings of Eskdale, Gretna, Hoddam, Luce, Pennersax and Trailtrow, all apparent early contemporaries of Bonshaw, but alas we cannot link these pedigrees to Irvings living today, whether members of our Study or otherwise.  See Chapter 16.2 of my book The Irwin Surname: its Origins, Diaspora and Early Branches.

Alas determining the identity of “*” SNPs (which have been "discovered" by L555 Pack tests) will involve at least one member in each of these new groups taking a BigY test (possibly with the costs shared amongst other members within the group), and then the other members in this group taking a new single SNP test.  At present such action is only justifiable for members who have tested FGC34569+ but negative for all the known sons of FGC34569, and for the descendants of the large "*" son(s) of FGC34569.  Several BigY tests have been ordered on this basis, and have identified "new" SNPs.  These have not yet been incorporated into the L555 Pack Test.

The immediate priority is for those Border Irwin members who have not yet taken a L555 Pack or BigY700 test to undertake at least the former and, with its new lower prices, preferably the latter.  

All the other branches in the Study are much smaller that the Borders branch, the largest containing only 16 members.

3.2  Aberdeenshire branch.  These testers are members of the lineage of Drum.  One of the prime objectives of this Study has been to test the tradition recorded by Dr.Christopher Irvin in c.1680 that William de Irwyn, to whom Robert the Bruce gave the forest of Drum in 1323, was a son of Bonshaw.  At face value these DNA results now imply the present senior male representatives of the Bonshaw and Drum lines do not share a common male ancestor. Expressed another way, these results mean that either:

For further details on this issue see the accompanying Supplementary Paper No.4 ("Interpreting Drum ....") where it is shown that Scenario (A) is most unlikely.

3.3  Sixteen members claiming descent from ‘Orkney’ ancestors apparently represent two branches having different paternal ancestries.  A possible relationship between these two lines is shown in slide 36 of Supplementary Paper No. 9.  Contrary to tradition, it is now clear that neither of these two branches is descended from either Bonshaw or Drum.  This in turn means that the American author Washington Irving (1783-1859) is not a descendant of Drum.

3.4  Shetland now has four branches genetically unrelated to one another, or to Orkney or other branches.  However despite the excellent genealogy Shetlands now have access to (, no genealogical links have yet been identified. 

3.5  Six members whose DNA signatures confirm they are distant cousins from a ‘Perthshire’ branch.  It is still unclear whether this branch is an NPE or adopted their name from a laird, perhaps the laird of Drum. 

3.6  One member whose ancestors came from 'Forfarshire'. As with the Perthshire name, the origins of this branch are unclear.

3.7  The Newton family is another branch of the surname whose origins are unclear.

3.8  NPEs.  Although members in the 18 small NPE branches (Beattie, Bell, Carruthers, Dodd, Elliot (2), Fleming, Graham, Johnston, Kerr, Kincaid, Latimer, Little, MacFarland, Napier & Todd plus one unknown) today all use the surname Ervin/Irvin/Irvine/Irving/Irwin, their DNA tests show they share a common ancestor with many in the Borders clans of these surnames, implying a NPE in their ancestral lines, probably in the 13th-17th centuries.  The Borders Reivers website used to state:

“The intermingling of peoples along the Anglo-Scottish border produced a tough, hybrid culture claiming many lines of descent.  It is unlikely that all the members of any Border family were descended from the same ancestor.  The pervasive social upheaval increased the chances that men sired by members of one clan might be born or raised under the surname of another.  So did the matrimonial customs of Border families, which encouraged trial marriages and allowed wives to keep their maiden names.  Moreover, the clans themselves were political entities as much as families, and many men adopted the surnames of other clans to obtain their protection and a franchise on their power.  There is [also] particular uncertainty in the case of the Scotch-Irish, as much of their genealogy was lost or scrambled when they were forced to resettle in Ulster.”  

3.9  Ten other small branches have been identified (UE, UI, UJ, U4, U5, U6, U9, U10 (formerly Nixon), U11 and U12) but their origins are still Unknown; most are probably Scots or Scots-Irish;  some may be recent NPEs.  One of these branches, U4, now has two BigY700 testers and I have been able to construct a mini-haplotree for these two men.

3.10  Uniquely to this Study the small Ireland - Drumcarney branch shares the R1a haplogroup, but do not match any other surname that has tested with FTDNA.  They are probably a Scots-Irish family.

3.11  The 'Ireland - ?Leinster' branch shares a common ancestor whose haplogroup 'I1a' is quite different to other members.  The origin of this branch may be the gaelic family O'Hirewen from Leinster in Ireland, that was later anglicised to Irwin, but further evidence is needed to substantiate this possibility. 

3.12  The small ‘Ireland - Munster’ branch, formerly thought to be three separate branches, shares the same SNPs and so is now regarded as a single branch.  The paternal ancestors of one member, Terrance Irwin, came from Co. Limerick and their gaelic surname O’Ciarmhachain was anglicised to Irwin.  His excellent story at is a "must read" for all members of this branch of our surname.  It is clear this branch never had Scottish connections, but in contrast have a proud celtic history. may also be of interest, especially pp21, 42 and the bottom left corner of figure 4b.  Members of this branch are recommended to join the Munster Irish DNA Project ( ).

3.13  Two small 'Ireland - Roscommon' branches have been identified.  The Roscommon - Rathmoyle branch includes the senior representative of this line, which was settled there in 1584, i.e. before the "Plantation" of the early 17th century.   Their DNA suggests the line is a NPE of the Rutledge family, a Borders surname.  The Roscommon - Roundfort branch is also apparently a NPE of the native Leinster family of Reilly.     

3.14  The small ‘Germany/Netherlands’ branch shares a common ancestor who evidently had the surname Arwine or Arnwine and migrated from Germany or the Netherlands (see  Subsequently, perhaps in the 18th century in New Jersey or SE Pennsylvania, it seems the name became confused with unrelated neighbours named Erwin.  It seems likely none of these members ever had Scottish connections.  We also have what appears to be a NPE of this branch. 

3.15  An 'Africa' branch is represented by an African-american whose ancestors were slaves, and probably took their surname from their slave-master.  

3.16  About 6% of the members are classified as Singletons until a closely matching participant joins the study.  Some of these Singletons may turn out to be recent NPEs.

NB  Not included in these statistics are a few testers, known as False Positives, whose surname does not sound like Irwin but who claimed to be Irwin NPEs.  Such “matches” can probably be attributed to "convergence" of random mutations, and are unlikely to have a genealogical relationship with any Irwin etc.