Looking into possible family 'y' I kept getting hits for DNA. Many research groups are trying to trace the patrilineal line back using the y chromosome DNA. Y DNA is only passed from father to son making it possible to trace it back in history. The Jewish researchers are especially interested in tracing their lines and possible finding a way to test for Jewish ancestry. Y-chromosomal Aaron is the name given to the hypothesized most recent common ancestor of the majority of the patrilineal Jewish priestly caste known as Kohanim (singular "Kohen", also spelled "Cohen"). Maybe all the testing of DNA is to find a specific line or to prove their claims.