First we consider where the surname Grant is to be found. Two good sources that give the whole of Ireland are Griffiths (largely taken between 1848 and 1864) and the 2008 telephone books
Grant distribution - Griffiths 1848-64.
Grant distribution - phone book 2008
There are perhaps 4 different sources of the surname Grant in Ireland, and one should therefore be able to pinpoint their origins using DNA
1. The Norman Grants who settled in Kilkenny and Waterford in 1169, lost their lands under Cromwell, and spread up into Tipperary and to Europe. There are two geographically distinct groups of Catholics and Protestants. You can see them clustered in the counties of Waterford, Kilkenny and Tipperary even today. These are probably the group that spread into Wexford and Wicklow.
My own dna is M222, which is odd in that my family should not have a NW Ireland y-dna, unless a Non Paternal Event has occurred. Comparison with other Grants from this group should enable me to see when the NPE occurred. My initial conjecture is that it dates from the Cromwellian wars around 1650.
2. Scots Irish settlers in Ulster, who one would expect to be Presbyterian. One would expect most of the Antrim Grants to come from this group.
3. The Newry, Armagh & Louth Grants who appear to have been native Irish who adopted the name. Today the majority are in Newry (114 of the 2008 Down entries have Newry post codes) I would expect this group to be Catholic
4. The Donegal Grants, who were virtually all Granny in 1850 and all Grant by 1910
5. A small group has appeared in Mayo, which I would assume to be a change of name by native Irish, and be Catholic.
|match in 37||R1b1b2|
21345 David Grant
|43215 Grant||25705 Grant (Louth)||Niall of Nine Hostages|
|3||19 (aka DYS 394)||14||14||14||14|
|28||YCA II a||19||19||19||19|
|29||YCA II b||23||23||23||23|
Grant Online Index