[Red Badger]

I thought, maybe incorrectly, that Mito-DNA was passable only through the maternal line............

[Coyoteman]

I thought, maybe incorrectly, that Mito-DNA was passable only through the maternal line...

mtDNA is passed from a mother to both sons and daughters. But only daughters pass theirs on to the next generation.

With sons, their descendants will have the mtDNA of their mates.

[ElkGroveDan]

I thought, maybe incorrectly, that Mito-DNA was passable only through the maternal line............

Correct. So this dead child would have the same mitochondrial DNA as his/her sisters, as well as his mother's sisters' girls. All of them COULD have gone ahead and passed on their mtDNA.