With match clustering, we compare not only whether you match each person, but also whether those people match each other. In addition to standard clusters, which don’t focus on any particular match, you can create custom clusters, which do. 

Pick a DNA match to find people who are related to them, based on a centimorgan (cM) range of your choice.

Why create custom clusters? 

Clustering around a certain match can help you fill in missing parts of your tree. Discover matches who share DNA with a match of your choice—likely because they all come from the same ancestor. You can even add up to four additional related matches—which we call “sidekicks”—to narrow your results even further.

Custom clustering goes beyond enhanced shared matches, showing you not just matches you share with a match, but also who’s related to those matches.

When you create a custom cluster, you can also choose the centimorgan (cM) ranges you want, from 20 cM on the low end to 1,300 cM on the high end.

How to pick a match of interest

• Pick a 2nd or 3rd cousin. If you have close cousin matches, choose a cousin related to you through your "brick wall" ancestor to find other matches connected to that ancestor.
• Look for unique clues. Prioritize matches with distinctive last names, unique locations, or trees that don’t overlap with your known relatives.
• Follow your curiosity. Choose a match who doesn’t fit into your known family tree, or who you’re curious about.
• Start with brick walls. Focus on a match who’s linked to a part of your tree where there’s an unknown ancestor.
• Check your shared matches. A good candidate may have shared matches you don’t recognize or can't place, hinting at an unknown branch.
  
  

Adding sidekick matches

Choose up to four sidekick matches—people who also descend from that same mystery ancestor. Sidekick matches must be shared matches with your primary match of interest. If your sidekick matches fall within the centimorgan (cM) range you select, then they don’t need to be added as a sidekick.

Setting the centimorgan range

Set the range for a custom cluster by matching it to your expected relationship to DNA matches (your cousins) who descend from your unknown ancestor.

1. Determine your relationship to your mystery ancestor.
   Are they a great-grandparent? A great-great-grandparent? You’ll use the number of “greats” to set your range.
2. Determine which cousins to include in the cluster. 
   If your ancestor is a great-grandparent, set your range for 2nd cousins (since you share great-grandparents with 2nd cousins). If your ancestor is a great-great-grandparent, include 3rd cousins (since you share 2nd great-grandparents with 3rd cousins). And if they’re a 3rd great-grandparent, set the range to target 4th cousins (since you share 3rd great-grandparents with 4th cousins).
3. Set the range.
   For example, if you’re targeting 4th cousins, set your range as 20–60 cM. If that gives you too many clusters, narrow your range to 30–60 cM. Adjust ranges and matches of interest until you find a group of matches you can’t fit into your tree.