Companies that offer genealogical DNA analysis usually provide tools to interpret the data, and you can use these tools to explore matches between you and people you share DNA with. If they appear on a public family tree you can try to connect to it from your own. If the tree is complete you will probably be able to find your most recent common ancestors.
You may also be able to find your more distant cousins by joining a project, a group of people working together to explore their common ancestry.
GEDMatch.com processes autosomal DNA data files from different testing companies to compare data derived from their DNA kits (‘autosomal’ means ‘concerning chromosomes that are not sex chromosomes’).
GEDMatch provides DNA analysis tools for genealogists, including tools for comparing your DNA test results with those of other people in the GEDMatch public database.
To use these tools you must first upload your DNA test results to GEDMatch. GEDMatch accepts results from the main testing databases at Ancestry.com, Family Tree DNA, MyHeritage, and 23 and Me.
A recent tool is Ancestor Projects. There are 38 projects presently registered WITH GEDMatch. Project members have DNA characteristics with whatever common trait or ancestry the project intends to explore. There are projects for royal pedigrees, deaf people, and connections from certain counties in Ireland.
I have joined the project for Cornish emigrants, which aims to identify DNA of emigrants from Cornwall. Greg has Cornish forebears. Members include people with GEDMatch kits who are descended from Cornish people who emigrated or from Cornish people who currently live in Cornwall. The new GEDMatch project tool allows the identification of matches and analysis of shared segments of DNA, with results limited to members within the group. The group shares information and communicates within a closed Facebook group.
So having joined the project what next?
If you are going to join a group I think it is a good idea to attach your family tree to your GEDMatch kit. You can upload your family tree to GEDMatch in the format of a GEDCom file which is a standard file type and which you can export from whichever program you currently keep your family tree in. You can create a link between a DNA kit and a person in your GEDcom. If you manage several DNA kits and they all relate to one family tree you can link the different kits to the right people on the family tree. The names and dates of living people are not shown when the tree is displayed in GEDMatch.
In the ‘Cornish Emigrants’ Facebook group we have a spreadsheet for sharing details. This shows who in the group is associated with which kit. It also lists the Cornish surnames in our family tree and details of our forebears who emigrated from Cornwall.
People in the group can run a report in GEDMatch to see which kits match their own and then begin a conversation to find connections.
The group started at the beginning of August. It has already gained 119 users and 182 kits.
I hope that by connecting with this project’s group members I will be able to extend our family tree and learn more about our family history.