Recompute family groups
This is the single most important housekeeping step in GDAT 4, and the one new users most often miss. Several analyses are empty until you run it.
What a family group is
A family group ties a set of your matches to a shared ancestral couple. When you recompute, GDAT walks each match's ancestor tree and tags every ancestor with the couple they descend from. That tagging is what lets GDAT answer questions like “which of my matches descend from this couple?” and “which segments came from that line?”
How to run it
- Import at least one ancestor tree (a GEDCOM import) so there's tree data to work with.
- Open Settings.
- In the Database card, click Recompute family groups.
- Wait for the confirmation: “Assigned N family groups across your match trees. The MRCA, Segment and Group Compare analyses now have data.”
What it enables
After recomputing, these screens come to life:
- Analysis → MRCA — matches grouped by the ancestral couple they share.
- Analysis → Segments — shared segments grouped by family group.
- Analysis → Group Compare — a group's ancestral couple across each match's tree.
- Research — per-family-group narratives and Confirm Ancestors.
Empty MRCA / Segments / Group Compare? They need family groups. If
you've imported a tree but these are blank, you haven't recomputed yet — or you imported the tree into
a different profile than the one that's active.
Re-run it after importing more trees. Family groups reflect the tree data
that existed when you last recomputed. Whenever you add or change ancestor trees, run
Recompute family groups again. (A GEDCOM import triggers a recompute for you automatically;
adding matches via a Client/CSV import does not.)
Surname analysis and clustering don't need this.
Surnames, ICW Clusters,
WIC, and CMA work directly on your raw
match/segment data, so they're useful even before you have any trees.