An example:
JOHN |
JOE |
PETER |
MIKE |
DAVID |
GEORGE |
FRANK |
MARY |
|
JAMES |
John is the father of Joe and Peter.
Joe is the father of Mike.
Mike is the father of George.
George is the father of Mary,
Mary is the mother of James.
Peter is the father of David.
David is the father of Frank.
Frank is the father of James.
John is the 2nd g-grandfather of James and
John is the 3rd g-grandfather of James.
Both statements are correct depending on the considered path.