The proposed relationship of Bartholomew Geary as the father of John Geary and Thomas Geary is supported by DNA evidence indicating shared ancestry within the family lines.

Specifically, DNA evidence confirms a distant cousin relationship between MFF (a descendant of the John Geary ancestral line) and JO (a descendant of the Thomas Geary ancestral line) with a shared segment of 13.07 cM across 1 HIR segments.

This match is consistent with their placement within these shared ancestral branches.