High Quality Content by WIKIPEDIA articles! Y-chromosomal Aaron is the name given to the hypothesised most recent common ancestor of many of the patrilineal Jewish priestly caste known as Kohanim (singular "Kohen", "Cohen", or Kohane). In the Torah, this ancestor is identified as Aaron, the brother of Moses. The hypothetical most recent common ancestor was therefore jocularly dubbed "Y-chromosomal Aaron", in analogy to Y-chromosomal Adam.