McCarthy Surname Study

About us

The McCarthy Surname Study seeks through Y-DNA analysis to place the various McCarthy lineages on the Y-DNA phylogenetic tree and to identify any genetic markers which might single out groups of McCarthys or their immediate predecessors. Apart from facilitating family connections among McCarthys throughout the world, it is hoped to identify the yDNA profiles associated with the leading families of the various MacCarthy septs and with other supplementary agnomens adopted subsequently to distinguish one McCarthy family grouping from another. Material such as charts, trees and presentations which cannot be accommodated within the webpages provided by FTDNA will be found on our supplementary website at MEMBERSHIP CRITERIA As indicated on our Results page, only about 30% of M(a)cCarthys can count themselves as paternal descendants of the eponymous Cárthach (d. 1045). These test positive for SNP ZS4606, or one of its two apparent 'sons', SNPs A5813 and ZS4598, or any SNPs which have occurred subsequent to these. Those of other surnames who test positive for any of these SNPs are now considered as progeny of Cárthach's paternal lineages and are welcome to join the Study. However this project intends to investigate the origins of all M(a)cCar(t)hys who acquired this surname through association with Cárthach's male progeny, and thus welcomes any participant who can supply a y-chromosome test sample representing a M(a)cCarthy family not known to have acquired the surname through a recent non-paternity event (NPE) or by corruption of another name such as MacArthur. McAuliffe, Cremin (and variants) and certain other surnames are also claimed in historical texts to have arisen from Cárthach's male progeny or from association with M(a)cCarthys early in the second millenium. Those of these surnames are welcome to participate in the study until and unless DNA analysis suggests such an origin is highly unlikely. Carty is likely to derive from one of a number of independent O'Carty septs scattered around Ireland, while McCartney is usually of an independent origin outside Munster. However, if participants of these names have haplotypes which are arguably representative of McCarthys they will be welcome to join the Study. From the above it will be appreciated that this Study is not concerned with mtDNA profiles. Female McCarthys with an interest in their McCarthy ancestry should persuade their McCarthy husbands, fathers, brothers, male cousins or uncles to participate by taking a Y-DNA test. Autosomal testing (such as Family Finder) is only pertinent to the Study as background information which potentially enhances genealogy implied in a Y-DNA test data. However our Co-administrator Zena (see below) has set up our sister site at to accommodate McCarthy pedigrees. This facility is intended for all project members, but a condition of our accepting non Y-DNA (Family Finder only) participants is that they provide a verifiable pedigree going back to (and hopefully beyond) a McCarthy male whose name, birthplace and approximate birth date is recorded within the last eight generations. A condition of membership for those who have tested 37 STR markers and are placed in McCarthy R-L21 Group B is that they will not object to being also joined to the R Z16526 and Subclades Project (formerly known as the R-P314 Haplogroup Project). Those placed in McCarthy R-L21 Group A will be asked also to join the R1b-CTS4466 Plus Project. Interested parties may join the project without submitting a Join Request. However this shall be on the understanding that those deemed not to meet the membership criteria indicated above will be asked to leave the project (or gracefully accept that the Project Administrator will remove them from it). ADMINISTRATION To share the workload and ensure the future of the Study, three Co-administrators now support this Study. Please send any queries relating to their specific areas of expertise directly to them, with copy to the Administrator. Nigel McCarthy - Administrator Zena McCarty Paice - Co-administrator (membership, Haplogroup R-U152 genealogy and McCarthy pedigrees (via our WorldFamilies sister site)). Fintan MacCarthy (McCarthy R-L21 Group B genealogy) Matthew McCarty (McCarthy R-L21 Group C genealogy / liaison with MacCarthy Clan Foundation)