Posted 2010-07-12 00:34 (#78447 - in reply to #76157) Subject: RE: Is Erik Barteit descendant of Grand Duke Gediminas?
I am glad to have this opportunity to help you understand more about the use of DNA for identity. As you correctly point out, there are known problems regarding the use of mtDNA, or "Mitochondrial DNA." This form of DNA passes exclusively from mother to daughter, essentially unchanged for many generations.
Because of the variability noted in mtDNA results within bodies, standardized test procedures include removing mtDNA from several regions of a body, not just taken randomly from the body itself. For living individuals, however, the standard is through cheek swabs.
However, the Rurikid studies you criticize are not mtDNA studies, which is for female lineage. The method employed to identify Rurikid and Geminidid lineages is the Y-Chromosome, or male line, Short Tandem Repeat (STR) method. Again, this method is based on standardized samples taken by cheek swab from male volunteers. The results are affected by two main factors: mutations, which are relatively rare but occur at a slightly higher rate than in mitochondrial DNA; and 'breaks' in a direct male lineage. The utility of such a method for evaluating patrilineage is obvious - if one were a direct male line descendant of a given ancestor, the Y-DNA STR would essentially pass unchanged through generation after generation, with very small differences over a given period of time, such as 20 generations.
The design of the aforementioned study is actually pretty elegant, because it enables comparisons of families with certain surnames with reliable pedigrees to test their relations with other families with purported conforming pedigrees. In general, these pedigrees appear to be accurate, and when several families with pedigrees are found to have conforming STRs, this strengthens the reliability of those genealogical charts in our skeptical scientific age, and likewise enables others to be evaluated for their pedigrees.
The royal genealogy charts, which were carefully protected, and carefully inscribed for centuries because of their importance, are proving to be generally pretty reliable. The importance of this is obvious - it protected a realm from usurpers, and helped guarantee reliable passage of government from parent to offspring.