Scots-Irish, Genetically Speaking

The Scots-Irish were descendants of Scottish settlers in Ireland.  Many of these Scottish settlers were in turn descendants of Lowland Scots that settled in Ulster circa 1609 to the early 1700s.  Others were descendants of Highland Scots from Argyll, the southern Hebrides, and Lennox, that settled in Ulster during the 1500s.  Both of these groups in turn were the descendants of the various Celtic groups indigenous to what is now Scotland.  Recent DNA testing has revealed that the dominated DNA haplogroups of the Scots-Irish are R-M222 and R-L21.  Below are illustrations that show the geographic locations of these two haplogroups.

map showing highest concentration of R-M222

maps showing highest concentration of R-L21