Re: Can a relationship be established from a mismatched marker
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In reply to:
Re: Can a relationship be established from a mismatched marker
Larry Walcutt 11/02/05
Not in any practical way. Absent a fortuitous mutation, DNA results are not useful for fine branching. The ranges for 95% confidence are very wide. Brothers may be a mismatch, while 10th cousins match exactly.
Unfortunately, media and testing company hype leads many to believe that DNA results are more precise than they really are. It is only with methodical testing that useful genealogical information can be extracted.
What these results does the other person is that he might be a descedant of your family progenitor. He should look through your genealogy in a top-down manner for possible connections. He may have to fill in those branches that haven't been traced.
DNA testing greatly facilitates the transition from a bottom-up research strategy to a top-down strategy. In the past people have tried it by looking through various genealogies of the surname. However, the task was usually overwhelming, as there were too many possibilities. Testing is able to eliminate most, thereby focusing research on fewer lines.
If a surname project has diligently collected and tested documented genealogies, results can be very useful to those from "orphan" lines. Each family should determine its ancestral haplotype by testing descendants of two or more sons of the progenitor until there is a match. If there are no matches with three lines tested, the best 2 out of 3 values on each marker can be used.
If enough markers are tested, markers that define an early branch (branch tags) can be found. They must be verified as ancestral in the same manner as the progenitor's haplotype. They can be very useful indication of a possible connection.
However, there is always the possibility of two independent mutations (parallel mutations) of the same marker, especially with faster markers. Thus, it they must be used with caustion when there is no supporting paper trail.