Research Thresholds
Longest segment cM
20
AScM minimum
12
Longest segment
27 cM ✓
Long enough to stand above background noise. Likely a connection within the last 4–5 generations.
17 cM ✗
Real, but likely traces too far back to document on a family tree.
AScM
Total shared cM รท number of segments. A higher number means the shared DNA is concentrated in fewer, larger segments. Lower means it is scattered across many small ones.
14.2 ✓
Strong signal. The shared DNA is concentrated in larger segments. Likely a meaningful, traceable connection.
11.1 ~
Worth a closer look, but pursue green matches first. Come back when something else lines up: shared matches, surname variants across both trees, ancestral towns in common, or a tree that’s heading somewhere.
8.3 ✗
Likely background noise. The DNA is real, but it probably reflects ancient shared Ashkenazi ancestry rather than a specific recent connection. A high total cM here is rarely a useful lead.
Even a high total cM doesn’t mean a close match. When AScM is low, the connection is likely ancient. Prioritize concentration over volume.
Defaults reflect the working consensus of the Jewish genetic genealogy research community. Adjust to fit your research context.
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