> undiscovered checksum scheme

I don't think checksum is a fair metaphor for anything happening in biological systems.

> Most mtDNA between humans is the same

And most DNA is also the same. A percent difference is the kind of thing that would require millions of years of divergence to develop.

> mtDNA is only 16,569 base pairs long

This is really not so precise. There will be a mixture of lengths due to insertions and deletions, even in the same individual, even in the same cell.

> The differences between mother and child are almost always due to the father's contribution, and not to mutations.

Do you have a citation for this?