mitocondria DNA--mitocondria are part of cell that have their own dna. only a woman's (mothers) mitocondria are passed down.

trouble is, i don't think there is that much difference- from one generation to the next.

its interesting to look as someone like the "cheddar man" a mummified bog man, and learn that 25% of the people in Cheddar share the same mitocondria dna-- 1500+ years after he died, but its not completely reliable for close relation as i recall.

booth came from a famous acting family, his father and his brother were well known. i suspect there are some relations about, and enough make an educated guess. (unless of course, he was an paternal event (isn't that the term?))