The proposed relationship of Frank Granstrom as the father of Gurli Granstrom and Stanley Granstrom is supported by DNA evidence indicating shared ancestry within the family lines.

Specifically, DNA evidence confirms a 1st cousin, once removed relationship between JP (a descendant of the Gurli Granstrom ancestral line) and FG (a descendant of the Stanley Granstrom ancestral line) with a shared segment of 434.89 cM across 15 HIR segments.

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