What kind of genetic test would be needed in this case?

If historians want to learn about a historical figure's maternal ancestry, can they test any of their descendants?





For example, if I wanted to find out the ethnicity of Abraham Lincoln's' mother, could I test one of Lincoln's descendants? Would I have to test one of Lincoln's sisters' descendants instead? How does this work? Thank you!What kind of genetic test would be needed in this case?
You would look at the mitochondrial DNA sequence of Lincoln. Mitochondrial DNA is only passed through the mother, so it is the best way to look at maternal ancestry.





Conversely, if you wanted paternal inheritance you would do Y chromosome sequencing since Y chromosomes are only passed from father to son. Only downside is that women don't have Y chromosome so to get paternal inheritance you would have to get a brother's DNA.