DNA matches can be confusing for a variety of reasons. For me, the main reason for the confusion is individuals to whom I am related to in more than one way.
AncestryDNA had identified all the shared matches I had with one match as being matches to my maternal side. The matches that had been identified were consistent with that. Except for one. AncestryDNA indicated one of the shared matches was to my paternal side.
A person could be tempted to think that AncestryDNA was wrong–and it’s possible that sometimes they are. This is not one of those times. It turns out that this match (which AncestryDNA identifies as being a maternal match) is actually related to me four ways–through three different sets of maternal ancestors and one set of paternal ancestors. None of these relationships are closer than my 3rd great-grandparents.
The green match–shown with green on the image because part of their last name is “green”–only matches to other matches identified to as being paternal matches of mine. Those shared matches with the green match that have been identified (approximately 20%) are connected to me through my 4th great-grandmother who was a Dingman.
This was easier for me to determine because I’ve already determined some of my matches and my tree is about 75% known through my 5th great-grandparents. That helps with the analysis, but that’s not the point of this tip.
The point is that there may be a very small number of shared matches you have with a match that are related to you in a different way than are the other shared matches. This can take time to figure out. It is also why it is advised to determine as many matches as you can–even on the families in which you have no DNA interest.
You have a DNA interest in all your matches. The more matches you know, the easier it is to work on the ones you do not or the ones who appear to be related on your brick wall families who were likely your motivation to take a DNA test in the first place.