{"id":80528,"date":"2025-04-03T08:00:00","date_gmt":"2025-04-03T13:00:00","guid":{"rendered":"https:\/\/blog.familytreedna.com\/?p=80528"},"modified":"2026-03-13T15:42:01","modified_gmt":"2026-03-13T20:42:01","slug":"dast-cast-irish-surname-dna","status":"publish","type":"post","link":"https:\/\/blog.familytreedna.com\/es\/dast-cast-irish-surname-dna\/","title":{"rendered":"DASTs, CASTs, and the Quest to Reclaim Lost Irish Clans: \u201cGene-Ealogy\u201d and the New Era of Irish Surname, Clan, and Kindred Research"},"content":{"rendered":"

[vc_row][vc_column width=”1\/1″][vc_column_text uncode_shortcode_id=”248528″]By: Mike Fitzpatrick PhD\u00a0and Esther Fitzpatrick PhD
\n Originally published in Journal of the Fitzpatrick Clan Society, “Gene-Ealogy and the new era of Irish surname, clan, and kindred research”<\/a><\/em><\/p>\n

Using Y-DNA analysis, CASTs, and resources like the Great Book of Irish Genealogies, researchers are uncovering overlooked Irish clans and reframing long-held surname assumptions.<\/h2>\n

A recent FamilyTreeDNA blog, \u201cY-DNA Sheds New Light on the Medieval Genealogies of the U\u00ed Bri\u00fain Dynasty of Northwest Ireland<\/a>\u201d, which stemmed from an article by DePew, Gleeson, and Jaski<\/a>, is ground-breaking. The topic is familiar to those interested in Irish surnames, addressing the often-asked question, \u201cCan Y-DNA<\/a> be aligned with medieval Irish genealogies?\u201d<\/p>\n

Genetic and Traditional Surname Trees: Understanding DASTs vs. CASTs in Irish Genealogy<\/h2>\n

The approach the authors used to investigate the U\u00ed Bri\u00fain is by no means new, involving a comparison of Y-DNA-associated surname trees<\/a> with clan-associated surname trees \u2013 the neatly coined DASTs<\/strong> versus CASTs<\/strong>.[\/vc_column_text][vc_single_image media=”80529″ media_lightbox=”yes” media_width_percent=”60″ lbox_social=”yes” uncode_shortcode_id=”955725″][vc_column_text uncode_shortcode_id=”139218″]FamilyTreeDNA\u2019s wonderful Big Y Block Tree<\/a>, inspired by Alex Williamson, is a DAST, and many of FamilyTreeDNA\u2019s surname Group Project Administrators<\/a> publish their own DASTs. What constantly impresses is the attention to detail, the incorporation of both Y-SNP<\/a> and Y-STR<\/a> data, and the clever estimates of branch ages; as expected from scholars, DePew, Gleeson, and Jaski\u2019s DASTs are all of that.<\/p>\n

Why Genetic Evidence Needs Historical Context in Irish Surname Research<\/h2>\n

But, it is the cognizance of Irish surname complexities that takes their research to a higher level1<\/sup>. Not satisfied with tackling a single surname and trying to prove a point by linking it to the surnames of a few well-known patrilineal cousins, the authors took on a puzzle of dynastic proportions \u2013 literally. This is praiseworthy because CASTs that focus on only small circles of historically connected Irish surnames can be fraught<\/strong> since they may fail to recognise that it is not uncommon to find parallel surname connections among different Irish lineages, which further might be expected to have quite different Y-haplotypes.<\/p>\n

When Surnames Mislead<\/h2>\n

As the authors say, \u201cSometimes the same surname arose independently in several branches.” This happens more often than imagined, yet may be obscured from sight. For example, the magnetism of a “big clan” surname<\/strong> and the allure of having a notable ancestor versus a less attractive “small clan” alternative can leave genetic genealogy hounds barking up the wrong tree<\/strong>. Such “dominant narratives<\/a>” can greatly hinder or even utterly blind.<\/p>\n

Challenging the Irish-American Genealogy Myth<\/h3>\n

Catherine Nash writes<\/a>, \u201cDiasporic genealogy is as much about enacting distinction as it is about making connections<\/strong> \u2026 the public culture of Irish-American genealogy is dominated by references to ancient Gaelic kings and clans.” DePew, Gleeson, and Jaski gain our applause for having none of that; with them, there is no cherry-picking. Yes, while on the one hand they identify Y-haplotypes that \u201cmatch very well\u201d some U\u00ed Bri\u00fain lines, such as the \u00d3 Conchabhair Donn (O\u2019Connor Don), they found others \u201cdo not fit into any of the genealogical schemes\u201d.<\/p>\n

And the authors\u2019 approach signals a new era has dawned on Irish surname, clan and kindred research<\/strong>, what we have elsewhere referred to in a recent publication as working the hyphen of \u201cGene-Ealogy<\/a>\u201d \u2013 and it\u2019s a moment of celebration. The dominant narrative era, in which the big heroic and anti-heroic narratives popularised in some Irish history books and pedigrees, is passing, and we are entering a phase of much deeper scholarly interrogation and understanding of Irish clans and kindred groups and their surnames<\/strong>.<\/p>\n

Now, some may squeal \u2018revisionist\u2019 and squirm at the upheaval and trauma that is being brought to bear on long-held surname identity beliefs. For others, revised positions are long overdue, part of a reversion to pre-colonial understandings of surnames, clans, and kindred. And while there needs to be sensitivity and respect for what has gone before<\/strong>, because some of it will remain accurate, there has come a deep desire to understand the occurrence of Y-DNA discovered Irish surname clusters that are possibly indicative of \u2018lost\u2019 clans and kindred groups<\/strong>.<\/p>\n

A Call for Clan Accuracy and Inclusion<\/h3>\n

Finte na h\u00c9ireann (Clans of Ireland)<\/a> is the independent permanent authority established to register Irish clans and historical families. Cathaoirleach (Chairperson), Gear\u00f3id \u00d3 Ceallaigh, has recently emphasized the importance of accurate differentiation within Irish surname groups and that clans and kindred be identified with their correct names and associated \u2018geographic areas in history\u2019.<\/p>\n

Further, he passionately stressed that Irish clans and kindred groups claim their identities<\/strong>:[\/vc_column_text][vc_single_image media=”80530″ media_lightbox=”yes” media_width_percent=”60″ lbox_caption=”yes” lbox_social=”yes” uncode_shortcode_id=”386085″][vc_column_text uncode_shortcode_id=”255424″]So we come to, how, then, do we \u201cdo\u201d robust research that explores the associations between Irish surnames and Y-haplotypes? The DAST bit looks very well covered, being in the good hands of Group Project Administrators<\/strong>, many so capable as mathematicians they could send their Irish clan flag attached to a can of Guinness up to the moon. The CAST bit is not easy, but we would do well to follow DePew, Gleeson, and Jaski.<\/p>\n

Why O\u2019Hart Remains Popular\u2014But Problematic<\/h2>\n

When it comes to Irish genealogies, many CAST endeavours tend to default to John O\u2019Hart\u2019s \u201cIrish pedigrees.\u201d<\/a> While DePew, Gleeson, and Jaski do make reference to O\u2019Hart, it is with a degree of caution. They note that O\u2019Hart\u2019s pedigrees are included in their research because they are a frequently consulted online resource.<\/strong> O\u2019Hart\u2019s pedigrees currently hold sway in many circles, but relying on them for advanced genetic genealogy is akin to trusting poit\u00edn to power the motor of a Porsche 911<\/strong>.<\/p>\n

Please pause for reflection. From the outset, reviewers received O\u2019Hart generously, yet bluntly: \u201cIn a future edition we trust to find it quite up to modern notions of accuracy.” Present-day Irish surname expert John Grenham pulls no punches<\/a>, \u201cEvery Gaelic Irish family is shown to descend from a single forebear, but only by constant jumbling of sources, unacknowledged guesswork and judicious omissions.” And Grenham\u2019s final words on the topic are, \u201capproach with caution.”<\/p>\n

Why CAST Research Needs More Accurate Sources<\/h3>\n

And here lies the not easy aspect of DePew, Gleeson, and Jaski\u2019s CAST method. We recognize that not only does one of the authors bring virtually unrivalled Irish genealogical scholarship, but the team also has access to sources many find out of reach<\/strong>. Yet, the difference between O\u2019Hart and the other Irish genealogical sources that the trio references is so stark, as the following summary attests, that it becomes crucial for forward-looking genetic genealogists to get access to those sources<\/strong>. The strength of engaging with “Gene-Eaological” research, which draws on DAST methods coupled with robust archival research, will bring needed rigor to Irish clan, kindred, and surname research, hopefully leading the hounds to bark up the “right” tree.<\/p>\n

How to Use the Great Book of Irish Genealogies (GBIG)<\/h2>\n

It is Leabhar Mo\u0301r na nGenealach (Great Book of Irish Genealogies, hereafter GBIG)<\/a> that serious researchers need to find a way to access. GBIG is not inaccessible, although only available in a few libraries<\/strong> and only purchasable at a price. However, for some context, one Big Y-700<\/a> costs about two-thirds of the beautiful shamrock green bound, five-volume set available from de B\u00farca books<\/a>. Also, (affording some Irish wit) the online version, exemplified in Figure 1, is free to view<\/a>.<\/p>\n

Comparing O\u2019Hart with GBIG is like comparing a skateboard with a spaceship. GBIG is the work of Dubhaltach \u00d3g Mac Fhirbisigh (Duald Mac Firbis)<\/a>, a seventeenth-century Irish scribe, translator, and the \u201clast great exponent\u201d of Irish genealogies. While a nineteenth-century review of Mac Fhirbhisigh\u2019s genealogies by Professor Eugene O\u2019Curry<\/a> was hyperbolic in its assessment \u2013 \u201cperhaps the greatest genealogical collection in the world\u201d \u2013 Eoin MacNeill<\/a> (1921) realistically called it \u201cby far the largest and fullest body of Irish genealogical lore.” A review of \u00d3 Mura\u00edle\u2019s edition<\/a> of GBIG declares it, alongside O\u2019Donovan\u2019s edition of the Annals of the Four Masters, one of the \u201ctwo greatest works that any modern Irish scholars ever accomplished.”[\/vc_column_text][vc_single_image media=”80531″ media_lightbox=”yes” media_width_percent=”60″ lbox_caption=”yes” lbox_social=”yes” uncode_shortcode_id=”310184″][vc_column_text uncode_shortcode_id=”130712″]<\/p>\n

GBIG\u2019s Value in Uncovering Lost Lineages<\/h3>\n

What can GBIG bring? By way of example, DePew, Gleeson, and Jaski mention O\u2019Connor clans. O\u2019Hart gives us eight O\u2019Connor pedigrees, much trimmed down, starting with \u201cO\u2019Connor (No. 1) Kings of Connacht\u201d, which feeds the dominant narrative, and even those brilliant of mind can be seduced. In contrast to O\u2019Hart, GBIG provides at least seventeen Conchabhair (Connor) surname genealogies across ten different population groups for a total of 375 individuals with the patronym<\/strong>. And that\u2019s not to mention 300+ distinct occurrences of the given name Conchabhair, the fifth most numerous in GBIG, via which a patronym, perhaps scarcely recorded, had a chance to have arisen (refer Figure 2).<\/p>\n

Insights into Surname Adoption and Fosterage<\/h3>\n

GBIG also brings perspectives to surname adoption, much in the way DePew, Gleeson, and Jaski highlight the factors that can influence “the precarious evolution of Irish surnames.” For example, in his genealogy of the seed or progeny of Conall Clogach, i.e., the folk of Maol Moich\u00e9irghe,\u201d2<\/sup> Mac Fhirbisigh noted, \u201cperhaps someone would examine this since other texts generally say Conall Clogach, son of Aodh \u2026 the reader should understand that it is possible, and even a custom, to refer to a person\u2019s fosterson as his son<\/strong> \u2026 and therefore one can, without contradicting this, call Conall Clogach “son of Aodh” \u2026 even though he be, according to this tract, Conall Clogach, son of Faolch\u00fa.”3<\/sup> That is, Mac Fhirbisigh considered that the difference in Conall Clogach’s genealogies probably came about because he was fostered<\/strong>.[\/vc_column_text][vc_single_image media=”80532″ media_lightbox=”yes” media_width_percent=”60″ lbox_caption=”yes” lbox_social=”yes” uncode_shortcode_id=”175336″][vc_column_text uncode_shortcode_id=”150033″]<\/p>\n

Other Key Genealogical Sources to Explore<\/h3>\n

Other easily accessible and essential yet largely underutilized genealogies deserve mention. Although unable to match GBIG, Corpus Genealogiarum Hiberniae<\/em> (hereafter, CGH) contains \u201cpre-Norman Irish and related tracts from the twelfth century;” those manuscripts are “Rawlinson B.502<\/a>” and “The Book of Leinster<\/a>,” \u201cwith variants and some additions from parallel material\u201d in “The Book of Lecan<\/a>” and the “Book of Ballymote<\/a>.” CGH is available from the Dublin Institute for Advanced Studies and can also be accessed online<\/a>, as can other vital works such as the \u00d3 Cl\u00e9irigh book of genealogies<\/a>.<\/p>\n

Correcting the Record: The \u00d3 Maol Ph\u00e1draig Lineage and the Fitzpatrick Surname<\/h2>\n

But the rewards of GBIG are by far the richest. Here, we recount some findings from the Fitzpatrick surname project. The dominant Fitzpatrick narrative once was that all surname bearers originated from the Mac Giolla Ph\u00e1draig dynasts of Ossory<\/strong>, the most notable branch being the Barons of Upper Ossory<\/a>, who were the first to take the anglicized surname form, by decree of Henry VIII. Hence, the early years of the Fitzpatrick surname Y-DNA Group Project<\/a> saw the \u201ccollaborative aim<\/a>\u201d of preparing a \u201cgenealogical register<\/a> of the male descendants of the 1st Baron of Upper Ossory in order to identify The Fitzpatrick, chief of his name.”<\/p>\n

No second thought was given to other ways the Fitzpatrick surname may have arisen, yet it did in several different circumstances, Van Morrison-like, \u201cfrom Bantry Bay up to Derry Quay and from Galway to Dublin town.” Finte na h\u00c9ireann now recognize five clans whose modern-day members all go by the surname Fitzpatrick<\/a>:<\/p>\n