The haplogroup of the ancient DNA matched the haplogroup identified in Michael Ibsen’s sample: haplogroup J. This haplogroup is relatively uncommon among people of European ancestry, and its presence in both the ancient sample and the comparators was a further point of consistency.
The researchers also checked the ancient sequence against a database of over 26,000 complete European mitochondrial genomes. The specific sequence found in the skeleton did not match any sequence in that database. This meant that a random coincidental match — a scenario in which the skeleton happened to share mitochondrial DNA with Michael Ibsen through some other pathway not connected to the documented genealogy — was extremely unlikely.
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## What the Y-Chromosome Said
The mitochondrial analysis was the most straightforward part of the genetic evidence. The Y-chromosome analysis was more complicated, and its results added an unexpected dimension to the story.
Y-chromosome DNA is inherited exclusively through the paternal line — from father to son, to son, to son, across generations. It allows researchers to trace an unbroken male lineage. Richard III’s Y chromosome should have been identical to, or very closely related to, the Y chromosome of any living male who traced his descent through an unbroken male line from a common ancestor with Richard.
The researchers identified a documented paternal lineage. Richard III was a descendant of Edward III, the fourteenth-century English king who died in 1377. Henry Somerset, the fifth Duke of Beaufort, was also descended from Edward III through a well-documented, if illegitimate, male line that passed through John of Gaunt. A group of living men could be identified as descended through that Beaufort line in an unbroken male succession down to the present.