If you are talking about Richard III and his identification, with DNA, they did two things, one try to trace a living Y chromosome descendant, that would carry the same Y as Richard, this didn't work as none of the men that were supposed to share the same Y did. However there is Mitochondrial DNA, this is the DNA located in mitochondria, this is only passed from mother to daughters, it is present in males but they cannot pass it down to their children, whereas if you are female you have the same mitochondrial dna as your mother, grandmother etc etc, it does mutate a little over time. John Ashdown Hill traced an all female lineage from one of Richard III sisters, Anne down to Joy Ibsen, she died in 2008, but when her son was tested to compare with Richard III, it matched, the only person that this matching Mitochondrial DNA could have come from was Cecily of York.
