Female inheritance
In sexual reproduction, mitochondria are normally inherited exclusively from the mother; the mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. Also, mitochondria are present solely in the midpiece, which is used for propelling the sperm cells, and sometimes the midpiece, along with the tail, is lost during fertilization. In 1999 it was reported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin to select them for later destruction inside the embryo.[61] Some in vitro fertilization techniques, particularly injecting a sperm into an oocyte, may interfere with this.[citation needed]
--------------------------- My reading suggests that Thomas Jefferson could not have passed his mtDNA because that is solely inherited from the mother -- in this case, Sally Hemmings.
There are some disputed cases, but the consensus is that mtDNA descends from the female line.
Of course the Hemings mitochondrial DNA was passed to her kids. But so was some Jefferson maternal DNA.
The mitochondria at real issue is Jefferson’s own, from his mother, grandmother, great grandmother ad infinitum. That is what they are trying to hang Jefferson’s purported fathering of Hemings’ issue on.
But the Jefferson mitochondrial DNA would have been inherited by a lot of the Jefferson line, and that is the source of the controversy.
Jefferson mitochondrial DNA could have wound up in Sally Hemings children through possibly eight different men who carried Jefferson mitochondrial DNA and may have consorted with Sally Hemings.
Still, the father passed a Y chromosome to Hemings’ children which corresponds to a haplogroup in the Jefferson line.
That is not proof that Thomas was the father, it is only proof that A Jefferson Male may have been. There were numerous Jefferson men who could have passed that on, and one of them was often at Monticello and socializing with the slaves.