Autosomal DNA

Stiles Autosomal DNA –

The SFA decided to expand our DNA project to include the utilization of Autosomal testing. We evaluated different site’s unique analytical tools. FamilyTreeDNA not only has a Family Finder test, but the site allows for individuals who have tested elsewhere to upload their test results to FTDNA, as does GEDmatch.

In March 2022, we created two groups, one with each site. Details about the projects and how to join were presented at the July 2022 SFA Annual Meeting. Autosomal testers with a family tree going back at least five generations and a Stiles among their line are invited to join.

As of July 2022, there are 18 members at FamilyTreeDNA and 67 registered kits managed by 28 members at GEDmatch. We are working with participants to get Family Trees entered or uploaded. Autosomal match results are reliable for 2^nd and 3^rd cousins and with reliable family tree details can take us further back six or seven generations. We are working in collaboration with the SFA historian and Stiles Surname (Y-DNA) administrator.

Interpreting Autosomal DNA Results

• Why don’t I match my second cousin once removed?
  • Your chance of matching close relatives all the way through the degree of first cousins (1C) is virtually certain. If they are second cousins (2C), the likelihood of a match is still better than 99%. At relationship degrees beyond 2C, the likelihood of a match to a known relative starts to drop more steeply. At third cousins (3C), the likelihood of a match is greater than 90%. If you were to test ten known third cousins, and they were not related to you in other ways, there is a good chance that one of them will not match. At fourth cousins (4C), the likelihood of a match is greater than 50%. If you were to test ten known fourth cousins, and they were not related to you in other ways, there is a good chance that five of them will not match. At fifth cousins (5C), the likelihood of a match is greater than 10%. If you were to test ten known fifth cousins, and they were not related to you in other ways, there is a good chance that only one of those ten will match and the remaining nine will not. There is more information on the probability that you and your known relative share enough DNA to match. Search “matching probability” at https://learn.familytreedna.com/
• John Doe and I match at Ancestry, but we do not match here in FTDNA. Why?
  • It depends on matching algorithms used by different laboratories, minimum centiMorgan threshold, longest blocks, and how fragmented your DNA segments are among your total shared centiMorgans.
  • Family Tree DNA: 9 cM minimal size block, or longest block of 7.69 cMs with a shared total of minimum 20 cMs.
  • com: 8 cMs shared minimum (formerly 6cMs; revised August 2020).
  • 23AndMe: 7 cMs minimal size block.
  • MyHeritage: 8 cMs shared minimum (formerly 12 cMs; revised January 2018).