GM_CommonAncestor Table

The GM_CommonAncestor table records tree people identified as common ancestors for a DNA match. Each row is one ancestor that appears in a match’s tree and has been flagged as shared. When the same ancestor_name appears across different kitb values, those matches share a common ancestor — a strong signal for grouping matches by genealogical line.

Data Source

Rows are parsed from the GEDmatch ClusterDisplay.php common-ancestors data. The tree-person first name is cleaned of HTML markup before being stored.

kita and kitb

kita is your (primary) kit — the base kit being gathered. kitb is the match kit whose tree contains the common ancestor (taken from the match’s kit number, falling back to the match URL).

Column Reference

Column	Type	Description
Id	int (PK)	Auto-incrementing primary key
kita	string	Your (primary) kit number. References GM_Kit.kit_num.
kitb	string	The match kit whose tree contains this ancestor. References GM_Kit.kit_num.
match_name	string	Display name of the match.
match_cM	decimal	Total shared DNA between your kit and the match, in centimorgans.
ancestor_name	string	The representative name of the common ancestor. Matching values across different kitb rows indicate matches that share this ancestor.
first_name	string	The ancestor’s first name (HTML stripped from the source markup).
last_name	string	The ancestor’s last name.
birth_year	string	The ancestor’s birth year.
death_year	string	The ancestor’s death year.
birth_location	string	The ancestor’s birth location.
death_location	string	The ancestor’s death location.
descendant	string	The descendant path / line linking the match to this ancestor.
tree_id	string	Identifier (tree URL) of the tree the ancestor was found in.
tree_name	string	Name of the tree the ancestor was found in.

Related Tables

• GM_CommonLocation — shared tree locations across matches, from the same ClusterDisplay source.
• GM_Match — the match summary; match_cM corresponds to the pair’s shared cM.
• GM_Kit — resolves kita / kitb to people.