How it Works
The GEDMATCH Burgess “Ancestors Project” will be the main source for the autosomal DNA data. There are testing companies where you can also use data in their database to identify matching segments. This is also acceptable data and will just need to be documented. As we progress on this effort, we may try to collect “tester names” from other test companies as possible way to perform additional analysis. But first we need to see how this is going to work.
Now it’s important to have validated matching segments. A match to a single tester with a common ancestor is not sufficient. That segment could be coming from anywhere in the trees and just because there is a common surname or ancestor in the trees does not mean the segment is coming from that ancestor. Four separate testers who are all first cousins or more distant cousins is required for a validated segment. The segment will need to be 8 cM or greater to be counted to try and eliminate matches just by chance. There is some flexibility in these requirements if a good case can be made.
One of the challenges of autosomal analysis is that once you start looking for common ancestors that are 4 or more generations back from the tester, then it is impossible to know from the DNA data along exactly where the common ancestor is between the two lines. It could be parents, grandparents, great grandparents, etc. You must use genealogical records in addition to the DNA analysis to identify where the connection is most likely to be.
Note that when a segment is identified and traced back to a common “Burgess” ancestral point, that point always has the possibility of coming from the mother or the father and thus it cannot be determined which of those contributed the DNA segment. It could follow the non-Burgess ancestral line from that point further back.
Keith Burgess at email address
Useful links:
https://dna-explained.com/2012/10/01/4-kinds-of-dna-for-genetic-genealogy/