There's some pretty nifty tools out there you can use to predict a possible relationship with a match based on the amount - either in centimorgan (cM) or percentage or both - of shared DNA. And that's very helpful in narrowing down which generation of your tree to look at in order to find your mutual 'most recent common ancestor' or MRCA.
However, many of those give you a range in which the amount of shared DNA falls, quite often covering numerous options. And I've found that, in my case, the prevailing theory often doesn't cover reality. As an example: the child of a second cousin once removed (2c1x) with whom I share 163cM, only shares 51cM with me. It took a bit of digging - she had a different last name, no public tree and was on another site - to uncover the father-daughter relationship. Predicted option #1, us being 4th cousins, was wrong, and we fell into the next lower probability category. And with my family this occurrence is a matter of rinse, repeat. Ad nauseam.
So for my own research purposes - because our predominant MRCA fathered children with two women, and it was becoming difficult to remember both who belonged where and how much DNA we shared - I made a chart of all known paternal matches so I had an overview of actual possibilities. It made and makes placing matches a whole lot easier.
And since I've gotten so much from this forum, I decided to try and do something for the community in return. So attached please find an abbreviated and anonymized version of said chart, covering the many variables of shared DNA among the descendants of several of the full and half siblings.
Hopefully you will find it useful.
(if you right-click and select 'open image in new tab' you will see the whole chart)
TD
EDIT - I accidentally attached an old chart, uploaded the newest one without errors. Sorry :/
