The maternal relationship between Irma Rose Fessler and her son
Donald Michael DeGrange is confirmed by the direct inheritance path of autosomal DNA down to their DNA tested descendant JD.
The segmental (via DNA segment triangulation) and total DNA shared between JD and other confirmed descendants of
Johann Baptist Fessler/
Elisabetha Maria Schmitz is consistent with the expected ranges for their respective relationships. Since JD descends from Johann Baptist Fessler/Elisabetha Maria Schmitz through Irma Rose Fessler and her son Donald Michael DeGrange, the presence of significant shared DNA between JD and other known descendants of Johann Baptist Fessler/Elisabetha Maria Schmitz validates the generational links along this maternal line.
This supports the conclusion that DNA was passed from MRCA couple Johann Baptist Fessler/Elisabetha Maria Schmitz through Irma Rose Fessler to Donald Michael DeGrange, and ultimately to JD, confirming this direct ancestral connection through multiple generations.