In April 2006, researcher Dr Ken Nordtvedt, identified another small grouping where the ancestral geographical area appeared to be predominately Irish, but the haplogroup was quite different from NWIrish and South Irish. As the third STR defined Irish grouping, it has been given the name 'Irish Type III'. Our O'Hearn family is included in this group as a branch of O'Brien of Thomond.
In November 2009, the FTDNA Walk The Y project discovered a new SNP, L226, that has since been found in all members of the Irish Type III haplogroup that have tested to date. A comprehensive website exists that has much information on this interesting Dalcassian haplogroup. See:- Irish Type III website link above.
This haplogroup originated in the counties of Clare, Tipperary and Limerick around the time of King Brian Boru who lived, 926 - 1014.