Thrift /Frith /Firth Surname DNA Project
Project administrator: Richard Thrift   rtx at cox dot net  (please include "DNA Project" in the Email subject line)
For the DNA Project's site map page, click here

Firth Family grouping based on Y-DNA marker values
using color to show differences between family groups.

The URL for this "freepages" site is long and inconvenient.
To refer to this page you can use the abbreviated form of the URL:   http://bit.ly/TFFDNA-firth_fam_grp
in place of the long version:   http://freepages.genealogy.rootsweb.com/~thriftzzfrithzzfirth/documents/firth_fam_grouping.htm


For each short tandem repeat (STR) marker tested, the number shown in the table embedded below is the individual's value for that marker.
Differences from the modal values for the family's haplogroup are color-coded; see the legend.
The markers that persist in a given family, differing from their haplogroup's modal values, are that family's CHARACTERISTIC MARKERS -a visual representation of the ancestral haplotype.
Characteristic markers can be used to separate haplotypes into family groups and subgroups by simple visual observation; see http://bit.ly/TFFDNA-fam_grp

Sharing a surname is an independent factor which increases the odds that two haplotypes of a given haplogroup are related; lacking a shared surname decreases those odds. For non-surname matches we need to be careful. In trying to determine whether matches to different surnames are relevant within "genealogical time," what matters most is the total number of markers compared, and the total number of mismatches. If fewer markers are compared, there is less confidence in a prediction that two haplotypes are recently related. Generally, the limiting factor when interpreting non-surname matches is the number of markers being compared. The best way to make a valid interpretation for the borderline cases is to get more data.
It is possible to compare the haplotypes of two people, using mutation rate estimates, to find the most likely "Time to the Most Recent Common Ancestor" (TMRCA) (in terms of either years or generations before the present) and the 95% confidence limits for the TMRCA. Focus attention NOT on the "most probable" TMRCA but on the confidence limits, that is, the earliest and latest times that are reasonable for the Most Recent Common Ancestor. To see examples of how broad the probability curves are, go Here, enter the Number of markers and Number of markers that match, keep the site's default mutation rate of 0.0033, click "Create graph," and notice the number of "transmission events" indicated under the leftmost and rightmost portions of the red curve. Divide the number of transmission events indicated at these points by two to get the number of generations back to the earliest and latest likely MRCA. Even with testing 67 markers, unless the matches are very close the region of reasonable probability covers a huge range of generations. (Keep in mind it is at most about 30 generations back to the time of the establishment of surnames.)
For more background, please see
http://bit.ly/TFFDNA-fam_grp and
http://www.familytreedna.com/public/Thrift-Frith-Firth/



There are five Firth/Furths tested so far. The pair descended from George Reyland Firth are father and son, but other than this pair, all tested independently and without knowing that the others existed. Since their characteristic markers match, it is clear that all four families descend from a common ancestor, apparently in West Yorkshire. The surprising finding that all four randomly selected Firths are from a single lineage would suggest that there are few distinct Firth lines. This is consistent with the relatively tight Firth surname distribution data. The large number of mismatches between the two who tested 67+ markers suggests that the Most Recent Common Ancestor (MRCA) lived long ago, giving time for several very old branches to arise. The multiple variations found strongly suggest that the single lineage of Firths can be divided into branches based on testing 67 markers. We need to test more Firths to 67 markers.

The Firth modal haplotype is an approximation of the haplotype of their MRCA, as far as can be discerned from the data at hand. Because several mutations have occurred in these lines since the time of the MRCA, when doing comparisons it is more accurate to compare against the Firth modal haplotype than to compare against the haplotype of any single one of the currently living Firths.

The surnames listed below with a grey background were identified by Ancestry.com as the closest non-surname matches in their database (there were no close matches in FTDNA's database). "Wildgoose," who traces to Aberdeenshire, Scotland in the 1700s, appears to be particularly closely related -is he? Although Wildgoose's haplotype only differs from the Firth modal by 2/43 (fewer mismatches than "Firth, b. bef. 1893, West Yorkshire"), he is lacking two characteristic markers, DYS 19 and Y-GATA-H4. To clarify Wildgoose's relationship to the Firths, more markers need to be tested. The other non-surname matches are not only more distant, but have all (except for Rix) tested fewer markers. It is less likely that these will have recent connections; still, testing more markers may change our view of situation.


[Use the left-right scroll bar at bottom of the table]