Genetic investigation of the patrilineal kinship structure of early medieval Ireland.

A previous study of Irish Y-chromosomes uncovered a likely patrilineal kinship basis to the most prominent early Irish tribal entity/kingdom, the Uí Néill, who dominated the North of the Island during the early medieval period (600-1,000 AD). However, it is unknown to what extent this was a general feature of the multitude of Irish kingdoms that existed over the same period. Irish surnames are patrilineally inherited in a similar manner to the Y-chromosome and their origin can often be traced to pre-existing tribal units. We genotyped 17 microsatellites in 247 Y-chromosomes from men with surnames that are purported to be derived from two different tribes (Eóganacht and Dál Cais) from the Southern province of Munster, as well as a third cohort of random names from the same geographic area. Although there is some sharing of Y-chromosomes between surnames of the same putative origin, there was no clear distinction between either grouping and the control, suggesting that the level of Uí Néill patrilineal kinship was not a universal feature of Irish tribal units. In turn this argues that an extensive extended clan or biological legacy of an eponymous founding ancestor was not necessarily a crucial factor in their establishment.