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O'Shea
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Y-Chromosome DNA and Surnames An overview As any person who has conducted genealogical research knows, there comes a point at which records no longer exist to document relationships. Until now, such documentary 'dead ends' meant that a particular line of research could not be pursued further. Now, with the advent of genetic genealogy, at least some light may be shed on certain suspected relationships that could not previously be documented. However, it is important to realize that genetic genealogy is a field in its infancy, and that there are definitely limitations to what it can and cannot prove. In the case of associating particular individuals with a surname (i.e., attempting to verify name relationships with DNA evidence), the present commercial tests are best suited to tracing male-line ancestry through a profile made up of anywhere from 10 to 25 markers (in tests presently available) on the Y chromosome. Since only males carry the Y chromosome, this form of testing can only be used to show male-line relationships. However, since surnames are generally passed on in the male line, y-chromosome testing can provide valuable clues or lend further evidence that certain men sharing the same surname may be related, and in tests of many markers, an estimate may be made with respect to the most recent common ancestor (MRCA). It is also possible to trace purely maternal ancestry using mitochondrial DNA (mtDNA), a form of DNA that resides outside the cell nucleus, and therefore only passed directly from mother to offspring. Unfortunately, mtDNA has a very slow mutation rate, making it less useful for showing relationships on a historical time scale. Other forms of maternal, as well as non-gender restricted testing are currently being developed. A good overview of both y-chromosome and mitochondrial DNA is given by Kevin Duerinck in his article, "GENETICS AND GENEALOGY: Y Polymorphism and mtDNA Analyses." With respect to Irish families of Gaelic origin, y-chromosome testing could be particularly informative. Gaelic family names are patronymic in nature - that is, they refer to a theoretical common male ancestor. For example, O'Shea comes from Ó Séaghdha, literally "descendant of Séagha," which, in this case, is supposed to refer to an ancestor of the Corcu Duibhne tribe in the 8th century. In the 12th century, according to various manuscripts, a branch of the clan migrated out of their native County Kerry in southwestern Ireland, and moved east into counties Tipperary and Kilkenny. Documentary records show that members of the clan were present in eastern Tipperary as early as 1298. Y-chromosome testing of groups of O'Shea (and variant spellings) men descended from both the Kerry and Tipperary/Kilkenny branches should theoretically show similarities in their results. Further, each sub-group should show closer kinship (i.e., fewer mutations) within the group than between the different groups. Having, for the past 12 years, collected a great deal of documentary information on the O'Shea clan (see the O'Shea Genealogy Project), I am hopeful that y-chromosome testing may clarify various relationships within and among the branches of the clan, and that it may provide some credible evidence linking individuals to particular branches of the clan when documentary evidence is lacking. Any male with the name O'Shea, Shea, Shay, O'Shee, or any of its variants, is encouraged to participate in this study. Also welcome are participants from other septs of the Corcu Duibhne clan group (O'Connell and O'Falvey of Kerry). For consistency, all participants are asked to use the service available through FamilyTree DNA. You will need to send a join request to receive an authorization code, allowing you to purchase the test at a reduced group price of $169.00. The testing procedure consists of taking cells from the inside of your cheek using a simple swab (provided in the Genetikit). The swabs are then sent to the lab for analysis, and the results are reported to you via a secure, password-protected web site. These results will also be forwarded to the Group Administrator, and will be posted on this web site in the Results area. Also, it is requested that you provide background information on the earliest known male-line ancestor by e-mail or by regular mail to me (see address below). I will then add those details to the data on this site. All reporting on this site will be done using a numeric code based on the order of the data's receipt, so that no personal information of the participant appears on the internet (apart from a contact e-mail address link, if desired). For the purpose of correlating genetic testing to documentary evidences, participants are asked to also provide a pedigree of their paternal-line ancestry as far back as it is known. Over time, we may thus be able to show with some certainty which paternal lines are most closely related. Please feel free to contact me with any questions about this project: Dr.
Patrick M. O'Shea |
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