A description of the tests done and tools used in the analysis of DNA matches. This includes the sites used and how to use the results of the family tests.
The DNA tests associated with the family genealogy are as follows.
Michael Jefferies; Tests on Ancestry, MyHeritage. Result connected to the Wansbury Family Tree on Ancestry. Y-DNA test on FTDNA at Y700 level.
Louise Simon; test on Ancestry; result connected to the Mead/Gough Family tree on Ancestry. DNA also uploaded to MyHeritage on Michael Jefferies’ account.
Nicholas Galton Jefferies; test on Ancestry; result connected to the Mead/Gough Family tree on Ancestry. DNA also uploaded to MyHeritage on Michael Jefferies’ account.
Melissa Clark; test on Ancestry; result not connected to a Family tree on Ancestry. DNA also uploaded to MyHeritage on Michael Jefferies’ account.
Elinor Nash; test on Ancestry; result not connected to a Family tree on Ancestry. DNA also uploaded to MyHeritage on Michael Jefferies’ account.
The resource numbers on GEDmatch are mainly for Michael Jefferies. The resource that combines to analysis of both tests (Ancestry & MyHeritage) is MX941038C1. The resource number for Nicholas Jefferies’ test is RT6486642. These resources are free to use for anyone with a GEDmatch account.
Ancestry has introduced an analysis that divides matches to paternal and maternal lines, or unassigned. This feature is very helpful when plotting DNA segments. My main tool for this is DNA Painter, in my opinion this has allowed links between matches to be explored most effectively. Much more work is being done to paint individual maps for each of the 5 tested family members and this takes time. The analyses done so far have shown some groups with, currently, no documented links to ourselves as well as confirming known family groups with common ancestors.
These results are being added to the DNA discussion pages on each family group, for example the Jefferies DNA page is Jefferies/Button.
The DNA analysis created by DNA Painter is at this link. Remember that this is a work in progress as more data is added and the way the data is handled may change over time as specific matches are labelled more accurately or reassigned to other lines.
Matches that involve shared segments below 10cM are known to be problematic. While we have some persons with known paper links found by matches of less than 10cM this can be misleading; the Blog 'The Genetic Genealogist' by Blaine Bettinger, has articles around this issue including THIS ONE if you are interested.
A summary of this article is:-
"Many to most small segments (at least 7 cM and smaller) are FALSE, meaning they are NOT actually shared by the two matches, and therefore do NOT indicate shared ancestry;
This is supported by a 2014 paper by 23andMe scientists showing that at least 33% of 5 cM phased DNA segments are false-positive (and it’s much worse for unphased segments or segments smaller than 5 cM);
This is further supported by evidence that anywhere from 20-35% of distant matches at a testing company are not shared with either tested parent;
This is further supported by evidence that phasing your DNA with two tested parents significantly reduces the number of matches below 10 cM (with proportionally more matches reduced as the segment size gets smaller);
There is currently no evidence that triangulating segments or finding a paper trail provides a mechanism for distinguishing between false segments and valid segments;
Since we can’t tell the difference between false small segments and valid small segments, we must avoid these small segments to avoid poisoning our genealogical conclusions with false data; and
Beware any research or conclusion that uses these small segments without specifically addressing the issues that are known – based on all the scientific research and evidence gathered to date – to surround small segments."
I am reaching out to persons who are identified by these processes and welcome any such requests. I have some very helpful replies in some cases and none, so far, in others.
The Y-Dna test was done at the Y700 level, the number of positions analysed which gives an accurate result back for some 3000 years. More details on this test and results are on the Jefferies specific page.
Revised July 2023