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 October 2022. These analyses will be next updated in May 2023.

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 2022 our Study has 608 members with yDNA test results. This total is less than the 659 members of the Irwin Clan Surname Project then advertised by FTDNA because the latter figure 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 to date 19

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 1

37 48

67 14

111 12

>111 21

i.e. 95% 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 and 111-marker tests 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 67 or 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 (or the cheaper L555 SNP Pack test) would be a much better investment.

126 (21%) of members have BigY test results, of which 110 (18%) are BigY700. A further 56 (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 608 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 (or variants thereof) (including NPEs)

On the basis of STR data it has been possible to identify 48 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 11 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 only indicative (experts differ on the exact dates). The purpose of this figure 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)

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 typically in the 18th or 19th centuries. 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 NPE's rather than False Positives.

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 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 BX (for the "left overs"). 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 plethora of sub-groups.

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 L555 Pack test or, preferably, a BigY 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, and if the narrow left-hand margins of sheets 2 and 3 are trimmed then the three sheets can be selotaped together. If you can't get a format that suits you 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 bold italics associated with many SNPs are the mean dates currently estimated by FTDNA's new "Discover More" 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 nearly 60% of all the members who are tested or predicted to be L555 positive 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 other descendants of Border Irwins shown on this haplotree do not extend back far enough in time to enable 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:

    1. The BigY700 test, particularly when taken up at FTDNA's new prices of $239-$339 (depending on resolution of existing STR testing) (and less in their frequent sales) now offers excellent value. It includes 50% more SNPs than the former BigY500. It also identifies up to 838 STRs, although the value of these additional STRs is proving to be very marginal.

    2. It is now apparent that L555 is the ancestor of a family of Wilsons (BY19631) and of a family of Grahams (BY14121), so the earliest SNP specific to Border Irwins is not L555 or Z16932 but probably one of the SNPs in the FGC13746 block. It is nevertheless still convenient to refer to Border Irwins as L555.

    3. The FGC13746 block has at least 6 "sons": FGC34569, FGC19539 (incl. Ewesdale branch), BY3690/BY3661, BY3712 (Dumfries branch), 11507432 and 16139804.

    4. The FGC34562/FGC34569 block in turn has at least 18 "sons", a very large "starburst". Starbursts are a term used to describe a large number of lineages following a SNP block or a single SNP. They are common in haplotrees covering the pre-surname era (see, for example,, but are still rare during the surname era. Their cause is unclear -it may be a feature of the individual haplotree, or may be due to environmental reasons. The Royal Stewart haplotree is the only other example of which I am aware. Both the Border Irwin and Royal Stewart starbursts may have been linked with the Black Death plague of the mid-14th century, but if so the relationship is unclear.

    5. These 17 "sons" include FT431998 (Cleuchhead branch), BY3701 (Castlederg branch), FT184892 (Augusta branch), FGC354024 (Westmoreland branch) and the newly discovered FT11934 which may be the "ancestor" of the Bonshaw branch, which is now appearing to be larger than had been thought.

    6. The L555 Pack test, at $119, is also good value for money for those L555 Border Irwin individual members who are (understandably) reluctant to pay for a BigY test, though this is being reduced. These Pack tests show from which branch of the Border Irwins they are descended more reliably than the sub-groups that have been tentatively identified hitherto using STR data. This means they can now seek genealogical relationships within their new SNP sub-groups with more confidence than they could with our old STR-based sub-groupsI.

    7. After combining these L555 Pack test results with L555 BigY test results and previously known genealogical data, our Study’s understanding of the origins and evolution of the Border Irwins has been improved considerably, as shown in the tree above.

    8. It is significant that all but one of the many members who were predicted to be L555+ on the basis of their STR test but had not tested for L555 who have now taken a BigY test or a single or Pack L555 SNP test have proved to be L555+. The sole exception was an NPE. This is as expected, but reassuring none the less.

    9. Although SNP Pack tests cannot identify “new” (i.e. unknown) SNPs, they have the unexpected bonus of their negative results indicating the existence of such SNPs. These “new” but unidentified SNPs are indicated by a stand-alone “*” or "?" in the haplotrees above.

    10. It is now also apparent that generally speaking by comparing the new SNPs under L555 with the tentative sub-divisions introduced in 2011 on the basis of single STR data, the tentative subdivisions BA, BE, Bel, Ber, B9, B10, B14 ,B15, B16, B17, B23 and B29 are misleading. The reason for these STR-based groupings are misleading is due to back mutations, i.e. although the counts for two members of a particular marker may be the same today, they were not necessarily the same 15 generations ago.

    11. However as most of the STR DYS617=11 sub-grouping (identified as “BB”) are consistent with the SNP groups BY3699, BY3656, BY3987 and (probably) the “?” of member #397497, it appears that our use of DYS617 = 11 is a pretty reliable indicator of the Bonshaw branch. This appears to have been confirmed by the new SNP FT12874.

    12. The L555 SNP Pack tests have confirmed that the Castle Irvine branch is descended from Bonshaw, but that the Dumfries and Eskdale branches are not.

    13. These Pack tests have also enabled the identification of BY3665 as a hitherto unrecognised "son" of FGC34569. This branch is evidently not a son of Bonshaw, but probably migrated to Co.Fermanagh in the 17th century and from there in the 18th century to Augusta County in Virginia. It thus seems appropriate to name this branch the Augusta branch, and as the ancestor of #432872 appears to have migrated separately it seems likely that the BY3665 mutation occurred in Ireland or even in Scotland. But to date the six members of this branch have not been able to determine their genealogical relationships.

    14. As more BigY and L555 Pack tests are completed it seems likely that these will enable further American branches to be identified and defined by their SNP characteristics, thus providing a reliable basis for interpreting the genealogical records of early American Irwins.

In the main L555 tree above I have discontinued my earlier attempts to calculate the TMRCA (Time to Most Recent Common Ancestor) of L555 using the theoretical average number of years per SNP (131 years for Y500, and 83.3 years for Y700). Instead I have counted the number of SNPs for each Y700 member descended from the FGC13746 block, a range of 3 to 14 SNPs with an average of about 7.6 SNPs, as shown in the histogram at the bottom left of the tree spreadsheet. If FGC13746 is the SNP of the earliest Border Irwin, and this man was born c.1310, i.e. 640 years before the average birth date of the members, this gives an average of 79 years per SNP. This seems no less credible that the converse of subtracting the product of 7.6 and 83.3 years (the theoretical mutation rate of Y700 SNPs), i.e. 640 years from 1950, giving the birth date of the earliest Border Irwin as 1310, which was before hereditary surnames were in general use in Scotland. But there are many uncertainties in both calculations. I now recognise there is another manual method of calculating TMRCAs ,"node-by-node", which give a mean of 6.3 Y700 SNPs from the FGC13646 block, giving a date of AD1350. All these TMTCA dates are estimated mean values of probability distributions with Confidence Intervals of two or three centuries.

These two manual calculation methods 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 FGC 13746 block, which BigY tests suggests 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.

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 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 BigY or L555 Pack test to undertake at least the latter and, with its new lower prices, preferably the former. It is now clear that the Pack test offers better value for money than upgrading from 37 markers to 67, or from upgrading 111 markers (although one day these upgrades may prove useful again). Each Pack test will help enable the individual to determine which son of L555 he is descended from and help him find other genealogically related members as well as improve our overall understanding of the origin and evolution of the Border Irwins. But for those that can afford it the BigY test remains optimal.

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:

  • (A) the 14th century ancestors of the Bonshaw and Drum lines did share a common ancestor, but there has subsequently been a Non-Paternal Event (see above) in one of the two lines, when the name passed through a female line; or

  • (B) contrary to tradition, the 14th century ancestors of the Bonshaw and Drum lines did not share a common ancestor.

For further details on this issue see the accompanying Supplementary Paper No.4 ("Interpreting Drum ....") where it is shown that Sixenario (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 three small 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 17 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 Twelve other small branches have been identified (UE, UI, UJ, U4, U5, U6, U7, U8, 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 several individuals, known as False Positives, testers whose surname does not sound like Irwin but who have a genetic distance of 4/37 or less and who have tested, or are expected to be, L555-. Such “matches” can probably be attributed to "convergence" of random mutations, and are unlikely to have a genealogical relationship with any Irwin etc.