The surname McGraw (and variants) is Gaelic in origin and can be traced back to two forms of the name in ancient Irish. According to Rev. Patrick Woulfe ( 1923), although it is frequently written as Mac Craith in Gaelic, the most correct forms are Mac Raith or Mag Raith. Father Patrick J. Ryan (2014) writes that an ecclesiastical family of historical importance in Ulster were spelled Mag Craith in the Irish Annals. In all cases, the surname means 'son of Mac Raith' and not 'son of Raith' as we would expect. This might be related to the fact that, unlike many other Irish surnames, it was not originally used as a last name. Rather, it started out as a personal name and written Macraith to mean 'son of grace' (or prosperity).

The earliest known use as a first name was by someone called “Macraith the wise.” He is identified in an old Irish poem describing some important members of St. Patrick’s household in the year AD 448. It was not until the 11th century that Macraith was adopted as a last name and this was by a prominent family of poets and storytellers in the southern province of Munster (formerly the ancient Kingdom of Thomond).  The first person in this family to make it a surname was known as Mac Meicraith. He was a grandson of Eichtigern (died 950 AD), the brother of Brian Boru who was a powerful Irish king from 1002 to 1014 AD. 

Another historically important family who changed Macraith into a surname had land in the ancient northern Kingdom of Ulster. These people were ecclesiastic and had lived on the western border of County Donegal since at least the 13th century. The earliest member of this family to use Macraith as a last name was Gilla Adomhnain Magraith, and he died in 1290 AD. The family later adopted the surname Magrath and their church lands around Lough Erne became known as Termonmagrath.

The first modern language to be spoken in Ireland was Irish Gaelic and it was introduced around the beginning of the Iron Age about 2500 years ago. Afterwards, Gaelic remained the primary language of the country until England took control of Ireland in the 16th century and began changing the names of people and places from Irish into English. 

Since most people in Ireland could not read or write, the English-speaking clerks who were responsible for anglicizing the Gaelic names had to rely on how the Irish words sounded to them. As a result, the “Mag Raith” surname became spelled in a number of different ways (see Table 1). By the late 19th century, “McGrath” had become the most widely adopted version in Ireland. [Note that the ‘th’ in Mac Graith is typically silent and the name is pronounced as ma-GRAH or muh-GRAH].  “McGraw” was ranked the 3rd most common version while “Megraw” held the 5th position. 

       
           Rank        Surname        Count

             1             McGrath        14,262

             2             Magrath           2,538

             3             McGraw            223

             4             McGragh            192

             5             Megraw            132

             6             Megrath              57

             7             McCraith             57

             8             McGrah               48

             9             MacGrath            37

            10            Magragh              16

            11            McGraith              15

            12            Magraw                14

            13            Macraith                2

            14            Magraith                1

            15            MacCraith              0

If we look at the geographical distribution of surnames based on the civil registration of births from 1864 to 1913, the “Megraw” surname was quite localized, being largely restricted to the counties of Down and Antrim (click here). The surname “McGraw” had a broader distribution and was predominantly found in the northern part of the country (click here). In contrast, the much more popular “McGrath” version of the surname was widely distributed throughout the whole of Ireland (click here).

An interesting thing about Irish-Gaelic surnames is that they can often be used by family historians to link an ancestor to a particular clan. This is because clans, by definition, are a group of people who share a common surname and have ancestral origins in the same locality. However, like many other ancient personal names that later evolved into a surname, “Macraith” appeared independently in different parts of the country and at different times. This results in the same derived surname (e.g. McGraw) being used by many unrelated families. 

Another complication are changes in the anglicized version of a surname. It is not uncommon find our ancestors recorded with a name different than what we expected and in some cases, these changes became permanent. Some known examples include McGrath to McGraw, McGraw to McGrew, Megraw to McGrath, etc. 

There is, however, an alternative to surnames for defining kinships and that is genetics.

Y-DNA, because it is passed from father to son over many generations like surnames, can also be used to identify potential ancestral connections to a particular kinship group. For example, the Thomond sept of the McGrath clan are descendants of the dal g Cais (Dalcassian) tribe in the southern province of Munster. In 2009, it was discovered that families of Dalcassian origin (e.g. O'Brien/Bryant, Hogan, Kennedy, McGrath, etc.) carry a genetic marker that defines them as members of the R-L226 (Irish Type III) haplogroup

Another useful genetic marker is defined by the R-M222 (Irish Type I) haplogroup. This marker is common in males from the north of Ireland and it has been shown to be most concentrated in the northern provinces of Ulster (40%) and Connaught (30%). It is also significantly associated with surnames that are linked to the Connachta and Ui Neill dynasties in northwest Ireland.  

Recently, this project discovered that R-M222  is carried by a direct descendant of Miler Magrath (c.1523-1622), Archbishop of Cashel. Miler came from a long line of distinguished coarbs (hereditary guardians) of  Termon Dabeog (later Termon-Magrath and Termonamongan) bordering the counties of Tyrone, Donegal, and Fermanagh.

Since this is a surname project our focus is on Y-DNA. If you have not already tested, we suggest using Family Tree DNA (FTDNA) which has the largest accessible database for Y genetic genealogy and a variety of excellent tools for analyzing your DNA results. Their standard starter test is Y-37, but the Y-111 marker test is preferable since it provides for a more accurate estimate of TMRCA [Time to Most Recent Common Ancestor] which other members with the same surname can use to determine if you might share a common ancestor.

If your budget allows it, your best investment is with the Big Y-700 test [Note: You are eligible for a substantial price discount if you have already done a Y-111 test]. It provides the most in-depth analysis of your DNA and the best measurable degree of paternal kinship to others, regardless of an individual’s surname. Of particular interest to our project is the Big Y-based Group Time Tree developed by Family Tree DNA (be sure to check out the "DNA Results", which can be accessed using the menu on the left).