Please test out this method and let me know what you think! Although I think it will be valuable for many genealogists, I think it will be especially useful for adoptees, Search Angels, and others who are trying to identify unknown, close relatives.
COLOR CLUSTERING: The Method
List all of your 2nd and 3rd cousin DNA matches. (Note: These are fictitious names, but the results are based on real matches.)
Assign a color to your first DNA match (for example, blue to Ralph.)
Open the shared matches for that person (Ralph), and assign them each the same color in the same column (blue).
Find the first person who does not have a color assigned (Robert), and assign him a color in the next column (orange).
Open the shared matches for that person (Robert), and assign them each the same color in the same column (orange).
Continue steps 3 & 4 until all of your shared matches have at least one color assigned to them.
COLOR CLUSTERING: Analyzing the Results
4 Columns/No Overlap:
If your results show 4 distinct clusters, like below, without any overlap, your sort is likely showing matches to your 4 sets of great grandparents.
Less than 4 Columns:
If your results show less than 4 clusters, it is likely these clusters represent 3 of your 4 sets of great grandparents and that you have no matches at the 2nd/3rd cousins levels who have tested for the 4th set of great grandparents.
If your results show 4 clusters but some of your matches have been assigned more than one color (for example, Herbert & Stacy are both blue and orange), your sort is likely showing either your 4 sets of great grandparents, but also showing you that two of these results (i.e. blue & orange) are on one side of your family. Or, the overlapped clusters (blue & orange) might belong to one set of great grandparents and, in this example, you are missing matches for 1 set of your 4 sets of great grandparents.
In this real example, there is a lot of overlap between all of the clusters except the yellow and brick red clusters. All of the overlapping clusters are on the maternal side of this test taker and visually show a lot of cousins marrying cousins resulting in pedigree collapse. The paternal mother's side is represented by both the yellow and brick red clusters. The paternal father's side has no cousins matching at the 2nd/3rd cousin levels. So, even though there are a lot of clusters and matches, this sort represents only 3 of the 4 sets of great grandparents for this individual.
A special thank you to everyone who allowed me to access their DNA and gave me feedback!
Please be aware: Your results may vary! This new method is still in its infancy and more test cases are needed to see how it works in various situations.
TIP: When I say "2nd and 3rd cousins," I am using the categories Ancestry has used to define them. The 3rd cousins appear to go down to 90 shared cM which works out well for this process.
TIP: If you chart is "too messy," look at the shared cM of your top matches and take off any that are above 400 shared cM. Then redo the chart. Hopefully, it'll be a lot "cleaner!"