R1b Eo´ganacht septs

The Sullivan surnames are being studied through the use of Y-DNA tests. The YDNA tests only the male lineage. The number of matching markers indicates the closeness of the genetic relationship between two families in genealogical time and the approximate time that the families diverged can be estimated. The results for the 67 markers are the most enlightening but 25 or 37 markers can place individuals in a Sullivan lineage.  

There are numerous surnames in addition to Sullivan that have returned as matches in the Sullivan Surname project. The reasons for the different surnames primarily are:

Non-paternal events:

• Adoption, stepchildren or other similar reason for diversity in a surname.

• Deliberate name changes:

  1. Adopting a Eoganacht surname when surnames were being adopted in 1000's AD. 

  2. Taking the surname of a dominant family in order to belong or enjoy protection provided by the surname: "It seems many males picked surnames or were essentially given surnames from the estate on which they lived and worked, but they had no recent relative status to the dominant family owning the estates.  So this cluster analysis is alive and well and could be applied to a popular surname like Sullivan", according to Dr. Ken Nordvedt.

  3. Changing a surname to obscure origin: Irish descendants may have changed their surname in order to assimilate into the U.S. in order to avoid persecution from being Catholic and/or Irish.

  4. Additional non-Sullivan surname matches likely occurred prior to the adoption of surnames in Ireland (900-1100 AD).  Families who lived in the same area without surnames may have adopted surnames when surnames became necessary/required/prevalent based on their current family group rather than the family group based on their DNA origins.

• "Result of female inheritance in which new surnames could be introduced could be introduced within a Clan noted in "Pursuit of the Heiress: Aristocratic Marriages in Ireland 1740-1840 by APW Malcomson.  Malcomson talks about a practice that was common in the 1700s called cadet inheritance.  Irish women could hold land in their own right, they could pass it down to the second  son in the family (first son always got the father's land and title) provided the second son assumed his mother's family name (i.e., his maternal grandfather's family name). So a genetic second-born son of a Sullivan-Driscoll marriage, for example, might end up a Driscoll.  This may not have happened frequently, but is another route by which "odd" non Sullivan surnames wind up being close matches, and why "Sullivans" end up in "non Sullivan" surname clusters."  Marge Sullivan

Name variants within a surname:

• The numerous nicknames Sullivans invented in order to differentiate among their more distant family branches over the centuries or because of a need to differentiate among the many Sullivans in an area or family.  These nicknames would eventually become surnames.

  1. Cadet branches or septs of the main Sullivan clan arose at various points in time as individuals attained fame or settled in certain areas---Sullivan Beare for example settling in Beara peninsula and Bantry in  West Cork. When name variants appeared for Sullivans, sometimes they were used like an additional surname, but sometimes they became surnames in their own right. Examples are: MacGillacuddy, McGrath, Scully, etc., Tiege or Teague,  all of which are connected to the greater O’ Sullivan Clan.

     1. Such as Bowe derived from Sullivan O'Buadhaigh (Bogue).

Examples of name variants in the Sullivan surname:

Dr. Gary B. Sullivan's book 'History of the O'Sullivan Clan describes McGillicuddy as a key player in Sullivan Clan history; see McGillicuddy. 

The additional names found in the 'Families of County Cork' include McGillicuddy, Haynes, Lynch, Watkins, and Brookes. See cadet branches. 

The common use of surnames in Ireland did not come into being until the 900-1100. Reading Dr. Gary B. Sullivan's book "History of the O'Sullivan Clan" provides a great deal of insight in the variations in names and naming conventions Reading through Gary's book you can easily see why names changed based on the strength of the person’s name becoming more prominent. So the Sullivan descendants would take a variation of his name which became a new surname. 

McGillicuddy

1043 AD "Buadhach[94], which translates into Victor, was the first in the line to officially adopt the name 'O'Sullivan'. It was not a family name in this time, but rather a title identifying the chief of the clan. Buadhach would have been referred to as the 'O'Sullivan Mor' or 'the Great O'Sullivan'". (pg 110). 

1166 AD Giolla Mochoda[97] the O'Sullivan Mor. "The O'Sullivan McGillicuddy sept is named after and also descended from this individual". Also read pg 116, 156, 180 and 195.

List of Sullivan septs pg 155-157

Related Gaelic Clans pg 159-163

O'Sullivan (the main line of the Milesian Celts, the most senior clan):

Cadet Branches of O'Sullivan clan:

·        Doran and Quaile Penfeather (O'Sullivan Vera)

·        Lawson (O'Sullivan Beara)

·        MacElligott (O'Sullivan McGillicudy)

·        MacGillicuddy (O'Sullivan Mor clan) also see McGillycuddy of the Reeks

Cadet Branches of the O'Brien (names also found in the 'Families of County Cork':

·        Lynch (see 'Families of County Cork, page 112 for link to the Sullivan's in Beara)

·        O'Neill

·        O'Hea (aka Haynes/Hayes/Hea/Hay see 'Families of County Cork, page 90, 91

Other match names include:

·         Watkins (see 'Families of County Cork, page 152) John Watkins was found in the 1659 census.

·         Brookes (see 'Families of County Cork, page 40)

·         Marsh (see 'Families of County Cork, page 114)