One tool I use all the time at the DNApainter site is the online shared cM calculator. This shows you the possible relationships that you have to a DNA match based on either the shared centimorgans (cM) or the percentage of DNA shared. It uses both the calculated odds from the DNA geek and the observed odds from Blaine Bettinger’s shared cM project. I find that these are far more useful than the predictions at the various testing companies.
Results of the online calculator for cousin “C’ sharing 1158 cM, red arrow points to new feature
When you input a number in the box at the top under the word Filter, you get a display like the one above which shows the likelihood of various relationships. Additionally those possibilities have their boxes light up in the chart underneath (click the image for the larger version which shows that). I used the 1158 cM that my first cousin “C” shares with me, on the high end for that relationship, to see what would show.
Do you see my red arrow pointing to the new feature? When you click on the words View these relationships in a tree you get a diagram like the one below, showing possible places for you in the tree of your match. Quick tip, right click those words to get a little menu from your browser letting you open it in a new tab or window. This diagram is created by the WATO (What Are The Odds) tool.
WATO for cousin “C” showing the menu for editing her in the tree (click for larger version)
One thing that takes getting used to for many of us genealogists, is that WATO uses a backwards pedigree format, a sideways descendant tree. The presumed common ancestor is on the left and the descendants fan out on the right. Every person in this diagram can be edited by the way. You can add names, birth years, whether they are half relationships, and so on.
Most people like visual displays of relationships so it is great to see the possibilities laid out in a family tree. Click the Continue Reading below for my experiments with some of my known cousins. However you may prefer to read about the details of this new tool by its author, Jonny Perl, on his blog (click here) – he does a great job of explaining it.
Also to learn more about WATO, click here for the Family History Fanatics youtube video or click here for Leah Larkin’s many more advanced articles on WATO.