Why are there so many different genetic signatures associated with a single surname? There are a multitude of reasons for why this may be so, and I discuss many of them in an earlier article here. 

However, in this article I want to focus on those potential causes that date back to the time of the Irish clans, prior to the Cromwellian conquest of Ireland. And this takes us back in time to a period prior to the demise of the Old Gaelic social system, a system that had been guided for centuries by a comprehensive legal system known as Brehon Law. (1) It recognised divorce, (some) equal rights for women, and defined offences and punishments in meticulous detail. The end of this system was signalled by a Proclamation of James I in 1603, which brought the Irish people under the "protection" of the English Crown.

Brehon Law was well-established in Ireland by the time surnames were introduced (roughly 1000 years ago on average for the O surnames, and 850 years ago on average for the Mac surnames). Most Irish surnames arose from an ancestor's forename (e.g. descendants of Chief Conor became O'Connor). Some forenames were very common (like Conor) and thus the  surname arose in several  places, over several hundred years, but from completely different origins. And hence the progenitors had completely different Y-DNA signatures, and were not closely related to each other. There are at least six separate O'Connor clans/septs recorded in Woulfe's surname dictionary (2) ... and in fact there are 34 distinct genetic subgroups in the O'Connor DNA Project (so far). Thus, one explanation for different genetic groups being associated with the same surname is that many surnames had  origins, each of them distinct from the others, and each with their own unique Y-DNA signature.

In 1916 for example, T J Westropp, the famous antiquarian, described the Limerick O'Malley's as one of several "petty tribes ... rather families than septs". (3) And indeed, there may have been several of these "families" within the Limerick area as there are now 6 subgroups under L226 in the O'Malley DNA Project, all with recorded (or likely) Limerick origins. I'll give some more examples in relation to the O'Malley surname below.

Another possible explanation for different Y-DNA signatures being associated with the same surname is the anglicisation of surnames, a process aimed at forcing the Irish to conform to English culture that saw surnames being translated from the Irish language form into an  English language form. (4) This long-term process was a key part of the English colonisation of Ireland and picked up speed during the lifetime of Grace O'Malley (1530-1603) with the passage of new laws under Henry VIII (1537) that essentially labelled the use of the Irish language as a sign of opposition to the English Crown. (5) Serious problems arose during the process of translation. Some surnames in Irish with completely separate origins were anglicised to the  English version. Thus A and B both became anglicised to X.  And so genetically we find that there are X's with an A genetic signature and X's with a B genetic signature - two genetically distinct groups with "the same" surname (or variants thereof). 

Conversely, anglicization also helps explain why there are so many variants of the O’Malley surname. There are several examples on the public Results Page of people who have the same Y-DNA but different surname variants (Malley, O'Malley, Maley, Melia, Malia, O'Meally, etc).

The Switching of Surnames

There were several important aspects of the Old Gaelic social system that could explain why different genetic signatures became associated with (for example) the O'Malley surname.

Some people switched their surname to that of the chief as a sign of their loyalty or fealty. (6) In this way, surnames of less powerful families "gravitated" toward more powerful families. Such a process has been termed "surname gravity" by leading medieval Irish academic, Bart Jaski (see his GGI2019 presentation here). Grace O'Malley herself (the famous Pirate Queen of Mayo) may have commanded such respect even though she was never formally a clan chief. In her biography of Grace, (7) Anne Chambers describes how Grace became “a matriarch, not merely of her own followers and extended family, but of neighbouring clansmen, whose chieftains had either died in the numerous conflicts of the period, or who had abandoned their obligations to protect their dependent followers.” Some of these refugees may have adopted the O'Malley surname as a mark of respect, gratitude and loyalty to Grace.

Strangers could be given the honour of being adopted into a clan (a form of citizenship) in recognition of their contribution to the clan community. (8) Some of these may also have had the O'Malley surname bestowed upon them (for example).

Some marriages resulted in the husband adopting the surname of the wife, especially if she was of higher social standing than he was. An apt example of this is the case of Oliver Cromwell, who should really have been called Oliver Williams. However, in 1497, his great great grandfather (Morgan Williams) had married Katherine Cromwell, sister of Thomas Cromwell, chief minister to Henry VIII. Morgan and Katherine’s three sons took the surname Cromwell in honour of their famous maternal uncle. Thus, Oliver Cromwell carried the Cromwell surname but Williams Y-DNA. Some family members later reverted to the surname Williams in order to distance themselves from their contentious cousin, thus executing a double-surname switch. (9) 

Some women retained their maiden name. After the death of her second husband (Richard Bourke) in 1583, Grace O'Malley herself used her maiden name (Grany Ni Mailly) in her exchanges with Queen Elizabeth I who addressed her as such in her replies. (10)

Under Brehon Law, marriage and sexual relations were approached very differently compared to today (and very very differently compared to the Victorian attitudes of 100-200 years ago). Ireland under Brehon Law was a much more sexually permissive society than one might imagine. It might be tempting to think that medieval society was like The Swinging Sixties, but better regulated and with everyone "on board", but promiscuity was frowned upon (at least female promiscuity), and was among the types of behaviour most frequently censured in women. (11) Furthermore, the introduction of inheritance by primogeniture (i.e. to the eldest son) led to a gradual change in sexual permissiveness in the 1600s, particularly for the landed classes. (12)

Most marriages were secular marriages based on the ancient customs - few people were married in church (13). Divorce was easy (for both men and women) and it was usual for the upper classes to have a string of different spouses. (13) This created an environment where the same surname could become associated with different types of Y-DNA.

Marriages usually started out as trial marriages for "a year and a day". (8) If at the end of the period, the couple were happy to continue as husband and wife, then they got legally married. But if they did not feel they could live together, they separated. Grace O'Malley famously did this with her second husband, shouting "Richard Bourke, I dismiss you" from the ramparts of his castle where she had installed herself and her followers, and locked him out. He can't have been very pleased to have lost a wife and a castle on the same day. (7)

Interestingly, if a couple separated at the end of the trial marriage, any children born to them during that time became part of the woman's kin (and thus presumably bore the name of her kin). (8) Thus if an O'Malley woman had a child during the trial period and then decided not to continue to legal marriage, the child would become an O'Malley but would carry non-O'Malley Y-DNA. Thus different Y-DNA was introduced to the wider O'Malley Clan.

Polygamy was allowed and it was common to have two or more wives. However, the term "wife" was more applicable to the first wife (the chief or principal wife). Subsequent wives had fewer rights than the first wife and might perhaps be more aptly considered as "concubines". (8,11,12,13)

The Brehon Laws refer to nine forms of sexual union. (11) The first three roughly equate with our modern concept of marriage, and the next four could be more akin to casual sex (referred to as "affinity" or "affiliation"), and the last two cover rape and insanity. The nine forms of sexual union are:

Why was it necessary to create these categories of sexual union? The reasons are probably complex and our understanding of them incomplete, but they had applicability with regard to the rights of children to inherit their father's estate, the inheritance rights of the different types of "wife", the division of property and wealth following divorce, and the legal status of the woman (i.e. under whose rule she came, how much fine was payable if she was killed or raped, and how much fine was due and payable by whom if she committed a crime). 

In cases of rape, forced abduction, or where the woman did not consent to the sexual union, heavy fines were levied on the offender, and the responsibility for raising any child of the union fell on the offender and his kin. (8,11) This applied whether the woman was married, unmarried, a servant or a slave. (11)

Sex with servants was apparently commonplace, both heterosexual and homosexual. (8,14) The children of any such union may have become the father's responsibility, and may have adopted his surname, but this is unclear and would have depended on the circumstances and whether the mother had any rights.

In certain circumstances, the woman alone was responsible for rearing a child (presumably with the help of her own kin). These included if she was a prostitute, or if the father was a stranger / alien (cú glas), a slave, a satirist, a man expelled by his kin; a dependent son, who impregnated her without his father's permission; or a priest who later repented. What surname the child took in these circumstances is not clear, but no doubt in many instances a son would have retained the mother's surname, and in this way, the particular surname could have become associated with different Y-DNA.

Brehon Law allowed for women to divorce their husbands under specific circumstances, (8,11,13,14,15) including:

Men also had grounds for divorcing a wife including: 

Furthermore women who left their husbands without just cause were stripped of their rights, denied shelter, and treated as outcasts. (8,11,14) There is no mention of this same treatment being inflicted on men, so the gender equality scales were not exactly balanced.

Another interesting example of grounds for divorce was if the couple were related by "affinity" i.e. if either party had had sex at any time in the past with a relation of their spouse, out to the level of third cousins. (13) Under Canon Law, the medieval church forbade marriage if the couple were 3rd cousins or closer, or if either had been married or had had sex (even once) with any of their prospective partner's relatives, out to the level of 3rd cousin. (How did they figure this out? Did they sit down and go through each other's family trees? Sounds like if you wanted to get married properly, you had to be a genealogist.)  If either party was previously married to a relative of the other (within the proscribed range), a papal dispensation would be necessary for the new marriage to be allowed and to be considered valid. Given society's relaxed attitude to sex, and the tendency to marry one's own kinfolk, it is likely that many marriages would not have been considered "valid"  in the eyes of the Church, but the couple managed to sail under the ecclesiastical radar ... or alternatively, could divorce each other at the drop of a hat. (12,13)

There were specific circumstances in which a couple could separate without being fined or penalised. Eleven such scenarios are listed in one book of Brehon Laws (Heptad 53) and these include death, entering the priesthood, and a variety of situations associated with temporary separation, such as going on a pilgrimage, searching for a far-off friend, going on a sea voyage, being in a revenge attack party, or being sick and requiring care away from home. But the most relevant situation with regard to Y-DNA is where the husband is infertile, the wife does not wish to divorce him, and instead goes away "to seek a child" by another man. The resultant child was treated as that of her husband - and in such a situation, the child would carry the husband's name but another man's Y-DNA. (11, p75)

Under Brehon Law, there was no concept of "illegitimacy" as we know it today  - every child was cared for by kin, no matter what their origins, be it a legal marriage, a casual fling, or an illicit tryst. In addition, there was apparently no social stigma, no concept of "the fallen woman" who had become pregnant "out of wedlock". Their attitude to such things was very different to that of (for example) 20th century Ireland. (8,11,13,14)

And these children, born outside of legal marriage, had equal rights to inherit their biological father's estate. (11,13) Just a few years ago (in 2022), legislation was passed by the Irish parliament that restored this prior right that such illegitimate children would have enjoyed under Brehon Law. The only thing that "out-of-wedlock" children were barred from doing was being a priest, apparently because "the child carried the sin of the mother".

In medieval Ireland, sometimes entertaining the guests went a lot further than just having them over for dinner. This is evidenced by the custom of "Naming" of children. In this case, a married woman, usually on her deathbed, would reveal that one of her sons had in fact been fathered by a man other than her husband, and usually quite a famous man with status, wealth and property. This newly illegitimized son thus became entitled to inherit the estate of his new father, but could also fall under his protection (thus securing his safety when his mother was no longer around to protect him). There are numerous contemporary examples of these "named children" and some of them (or their own children) became clan chiefs (e.g. in the latter half of the 1500s, James Meagh became chief of the O'More's, and Feardorcha O'Neill's son Hugh O'Neill became Earl of Tyrone). (13) Undoubtedly some of these "naming" events were pure lies, but this is another example of how different Y-DNA could become associated with a particular surname.

Fosterage was very common in medieval Ireland. Parents would give a child for fosterage to another family if they wanted to forge strong links with that family, or if they wanted their child to learn a profession. The period of fosterage was usually up to to seventeen years old for boys, and up to 14 years old for girls (after which they became nuns or wives). (11)

If a child was adopted (by a childless couple, for example), it is likely that they would have carried the surname (but not the Y-DNA) of the adoptive father. But if a child was fostered, then they probably retained the surname (and Y-DNA) of their biological father. The only circumstance where the fostered child might adopt the name of the foster father, might have been if the natural father died while the child was being fostered.

The way clan chiefs were elected changed considerably over time. The Irish clans operated under Brehon Law and the system of Tanistry, whereby a successor for the chieftainship would be chosen from relatives within the derbfine, i.e. direct male line relatives of the chief out as far as "the fifth degree of relationship" (roughly second cousins). (13) As a result, the Y-DNA signature of the clan chief should have remained relatively unchanged down through the generations, because subsequent clan chiefs would be related to him on his direct male line. However, it is possible that the DNA of the Clan Chief may have varied from time to time, if a DNA switch had occurred on the direct male lines of relatives within the derbfine. And thus (for example), the various genetic groups with Mayo origins that we see in the O'Malley DNA project today, may have been associated (at one time or another) with an O'Malley chief that carried their DNA signature. 

This Irish system of Tanistry was eventually replaced when the English system of primogeniture was foisted upon the clans (including the O'Malley's) following the Composition of Connaught in 1585. (16,17) Thereafter, the role of chief should have been passed from father to eldest son (the law was not always obeyed), thus probably reducing the opportunity for different DNA signatures to be associated with the role of clan chief.

So, to recap, the potential medieval causes for different genetic signatures being associated with the same surname may have included the following ...

1) History of the Law in Ireland. Available at the website of The Courts Service of Ireland.

2) Woulfe, Patrick. Sloinnte Gaedheal is Gall: Irish Names and Surnames, collected and edited with explanatory and historical notes (1923). Available at https://www.libraryireland.com/names/contents.php

3) Westropp, T.J. (1916) The antiquities of Limerick and its neighbourhood. Dublin: Hodges Figgis & Co. Available from the Archive.org website here. Note that pages 81 and 140 are missing from this version but can be found in this alternative version on the AskAboutIreland website here.

4) Murphy, P. The Anglicization of Ireland: A Model for the Linguistic Imperialist? Available online here.

5) Crowley, AE (2016) Language, Politics and Identity in Ireland: a Historical Overview. In: Hickey, R, (ed.) Sociolinguistics in Ireland. Palgrave Macmillan , London , pp. 198-217. ISBN 978-1-137-45347-1

6) Clan FAQs at https://www.scotclans.com/pages/clan-faqs

7) Chambers, A (2009, 7th edition). Grace O'Malley: The Biography of Ireland's Pirate Queen 1530–1603. Gill Books. Available from http://www.graceomalley.com/

8) Kerrigan, J (2020) Brehon Laws: The Ancient Wisdom of Ireland. Free Kindle edition available here.

9) Castlelow, E. Oliver Cromwell. Biographical article at Historic UK website available here.

10) Trowbridge, B (2016) Meeting Grace O’Malley, Ireland’s pirate queen. This article includes digital images of Grace's petition to Queen Elizabeth I (Catalogue reference: SP 63/170 f. 204) as well as the 18 "interrogatories" and her responses (SP 63/170 f. 201-202). Available at The National Archives blog.

11) Kelly, F (1988, reprinted 2016) A Guide to Early Irish Law. School of Celtic Studies, Dublin Institute of Advanced Studies. Available from DIAS here.
Prof Fergus Kelly is a Senior Professor in the School of Celtic Studies at the Dublin Institute for Advanced Studies (DIAS).

12) Simms, K (1975) The Legal Position of Irishwomen in the Later Middle Ages. Irish Jurist, vol.10, pp96-111. Available to read or download here.
Katharine Simms is Senior Lecturer in Medieval History in the School of Histories and Humanities, Trinity College Dublin.

13) Nicholls, K. (2003, 2012 digital reprint) Gaelic and Gaelicised Ireland in the Middle Ages. The Lilliput Press. Kindle Edition available from Amazon here. 
Kenneth Nicholls is a former Professor of History at University College Cork.

14) Duggan, C (2013) The Lost Laws of Ireland. Glasnevin Publishing. Kindle Edition. Paperback edition available here.

15) Ginnell, L (1898, reprinted 2011) The Brehon Laws: a Legal Handbook. Read Books Ltd.. Kindle Edition available from Amazon here. Also, freely available from the LibraryIreland website here.
Laurence Ginnell (1852-1923) was an Irish nationalist politician, lawyer and Member of Parliament (MP).

16) Cunningham, B (1984) The Composition of Connacht in the Lordships of Clanricard and Thomond, 1577-1641. Irish Historical Studies, Vol. 24, No. 93 (May 1984), pp. 1-14. Available online here.

17) McInerney, L (2011) The Composition of Connacht: an ancillary document from Lambeth Palace. North Munster Antiquarian Journal vol. 51. Available online here.

                                                          *******************************************

  

                                                                      SURNAMES  

The earliest known Irish surname is O’Clery (O Cleirigh); it’s the earliest known because it was written that the lord of Aidhne, Tigherneach Ua Cleirigh, died in County Galway back in the year 916 A.D.

In fact, that Irish name may actually be the earliest surname recorded in all of Europe.

Until about the 10th century, Irish surnames were not passed down from generation to generation. Instead, surnames were patronymic, or based on someone’s father’s name. A person was identified by his given name plus “mac,” meaning “son of,” followed by his father’s name.

For instance, Brian mac Colum was Brian, son of Colum. Brian’s son might be Finnian mac Brian (Finnian, son of Brian).

The female form of “mac” is “nic,” shortened from the Irish iníon mhic.

Alternatively, the prefix “o” was sometimes used in place of “mac” and meant “grandson of” or “descended from.” If Colum was well known, his grandson might have gone by the name Finnian O Colum.

There were no fixed surnames, so a surname changed every generation or two. That can make tracing your family tree a bit more complicated!

But even without hereditary surnames, those names still hold clues. For example, that person named O’Clery or O Cleirigh (or Ua Cleirigh) was the grandson or descendant of someone named Cleirigh. (“Ua” was an earlier form of “O.”)

O’Clery – Defendant from the Ireland Court of Chancery Records, 1641.

It was around the 1100s, as the population was increasing, that people in the upper social classes started taking hereditary surnames (those that remain fixed over the generations); others didn’t need surnames, or even get around to them, until the 1500s.

Another strong influence on Irish names came with the Norman invasion of 1169, when a lot of Anglo-French names came marching into Ireland (this, too, is when the Latin-derived prefix “Fitz,” meaning “son of,” first came into Irish names). It’s from this influence that some of the names we now consider Irish — Costello, Power, Burke, and others — first entered the scene.

And in the 1500s, the influence of the English was beginning to make itself felt in Ireland. Ireland was experiencing religious persecution and invasions, and many changes came to the island — including the changing of Irish names, steadily but surely over the ensuing years, into ones that sounded more English.

An example of this was the common Irish surname Mac Gabhann, which meant “son of a smith.” Some Mac Gabhanns, living in County Cavan, had their name translated to Smith and it remained that way. Others outside that area resisted, but the spelling became anglicized and they became Mac/McGowans. This was very common.

Also, in many cases the prefixes Mac and O were done away with.

Many surnames originated as occupational or descriptive names. That earliest known name, O Cleirigh (O’Clery), was someone descended from a clerk; Mac an Bhaird (Ward) was son of a bard; and Mac Labhrain (MacCloran) was son of a spokesman.

Descriptive names were names that described the first person to take them. The first person with the name Dubh (Duff) (“black” or “dark”) was probably dark featured. Other descriptive surnames include Bane (“white”), Crone (“brown”), and Lawder (“strong”).

Irish toponymic surnames, deriving from a place where the original name bearer once lived, are rare. They include Ardagh, Athy, Bray, Kelly, Sutton, and a few others.

The most common Irish surnames in Ireland haven’t changed much for a century. Here are 10 of them:

1. Murphy — The Anglicized version of the Irish surname Ó Murchadha and Mac Murchadha, meaning “sea warrior.”

2. Kelly — The origin of this Irish name is uncertain. An Anglicized version of the Irish name Ó Ceallaigh, it can describe a warrior or mean “white-headed,” “frequenting churches,” or “descendant of Ceallach.”

3. O’Sullivan — (Ó Súileabháin or Ó Súilleabháin in Irish). In 1890, 90 percent of the O’Sullivans were estimated to be in Munster. Many people agree that the basic surname means “eye,” but they do not agree whether the rest of the name means “one-eyed,” “hawk-eyed,” “black-eyed,” or something else.

4. Walsh — This name came to Ireland via British soldiers during the Norman invasion of Ireland and means “from Wales.” It’s derived from Breathnach or Brannagh.

5. Smith — This surname does not necessarily suggest English ancestry, as some think; often the surname was derived from Gabhann (which means “smith”).

6. O’Brien — This name came down from Brian Boru (941-1014) who was king of Munster; his descendants took the name Ó Briain.

7. Byrne (also Byrnes; O’Byrne) — from the Irish name Ó Broin (“raven”; also, descendant of Bran); this dates to the ancient Celtic chieftain Bran mac Máelmórda, a King of Leinster in the 11^th century.

8. Ryan — This name has various possible origins: from the Gaelic Ó Riagháin (grandson or descendant of Rían) or Ó Maoilriain (grandson/descendant of Maoilriaghain) or Ó Ruaidhín (grandson/descendant of the little red one). Or it may be a simplification of the name Mulryan. It means “little king.”

9. O’Connor — From Ó Conchobhair (grandson or descendant of Conchobhar; “lover of hounds”).

10. O’Neill — Anglicized from the Gaelic Ua Néill (grandson or descendant of Niall). The name is connected with meanings including “vehement” and “champion.” The main O’Niall family is descended from the historic “Niall of the Nine Hostages.”

Original article by Leslie Lang at Ancestry  https://blogs.ancestry.com/cm/history-of-irish-surnames-is-yours-here/?o_xid=127429&o_lid=127429&o_sch=Email+Campaigns