A Segmentology TIDBIT
Finding Common Ancestors with Matches in a Cluster sometimes “stops” at a specific generation – for example at the 3xGreat grandparent [4C] level. In other words, I’ve found cousins up to that generation, but not beyond. When one of these 3xGreat grandparents is a Brick Wall (or an “iffy” Ancestor), that’s probably the reason. The Cluster really goes back farther, but I don’t recognize any Common Ancestor further back.
It’s time to research and take notes.
I see three courses of action:
- If a surname is known or suspected, look in the Cluster for Matches with Trees and search them for that surname. Often, when I find one, I can build the Match’s ancestry out from there – looking for a link to my line.
- If a surname is unknown, jot down each Match’s surnames and try to find a Common Ancestor among them. Then I build the family around that Ancestor – looking for a link to my line.
- Alternatively, look for a common place and time approximately where the Cluster stops. Noodle around for any likely links. Check other Matches in the Cluster for those same links.
I use the Shared Clustering program which shows me the Matches for each Cluster, Common Ancestors from ThruLines, the number of people in their Tree, my Notes, and a hyperlink back to their AncestryDNA Profile. For each Cluster it’s easy to see potential CAs, then click on Match links, and see the surnames in common or call up their Tree for a more in depth review. It goes pretty quickly.
The result of these courses of action have ranged from easy “low hanging fruit” to “Mission Impossible”. In other words – sometimes it works, sometimes it doesn’t. I try these alternatives because they work in enough cases to encourage me to try more. I hope they will help you.
[22AT] Segment-ology: Clusters at Brick Walls TIDBIT by Jim Bartlett 20200507
segment-ology 
Great tips! A few questions:
1. Is there a specific clustering program you recommend? I best like Jonathan Brecher’s double match triangulation, but that may be because I have yet to learn to use Genetic Affairs, or the GEDmatch or MyHeritage cluster programs to the maximum.
2. Any advice for resetting default thresholds on Brecher’s program when trying to break through a brick wall? I do a complete scan, then collect everything a 6cM minimum.
3. What is the furthest brick wall you’ve been able to break through?
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David, Thanks for the feedback.
1. Yes – Shared Clustering – I wrote a blogged about it on 20 Nov 2019. I’ve used all 4 programs – see blog on 4 Apr 2019. All of them work well, but I get like the flexibility of Shared Clustering – plus the ability to change my Notes within the Cluster spreadsheet, and then upload them back to Ancestry. I’d recommend everyone try each of them at least once. Clustering is primarily for AncestryDNA, because you can create more difinitive Triangulated Groups at the other companies.
2. I always do a download at 6cM to get every Match at AncestryDNA – if nothing else it’s a great inventory, and an easy way to search for Matches – with a hyperlink to take you straight to their page. For Clustering, the primary run is on 20cM (the lowest level with Shared Matches). Once you do a download, each Cluster diagram only takes a few seconds. I’m experimenting with 25, 30, 35, 40, 45cMs – one might highlight a specific brick wall better. And with Shared Clustering, you can easily copy selected IDs and run a cluster diagram only on the kits you’ve chosen.
3. I’m focused right now on trying to link AncestryDNA Clusters to Triangulated Groups. I have completed mapping my chromosomes with 372 TGs. The issue now is extending the Common Ancestors for each one – and AncestryDNA has the best Trees for that (particularly with ThruLines which “covers” all of my known Ancestors out to 5xG grandparents. If I could link those ThruLines to the TGs I’d have a good chromosome map with CAs back 7 generations. My best so far is at the 3xG grandparent level (see the 5 Aug 2019 post). I’ve got several Clusters which stop at the 4xG and 5xG grandparent levels, and I get distracted on that tangent from time to time. I’ll do a “forced march” on several of them soon.
Jim
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