MORE ON THE GENETIC RESEARCH on the Jewish priesthood:

Study of Jewish lineages reveals genetic 'heirloom'
By Tom Beal
Arizona Daily Star
Tucson, Arizona | Published: 09.24.2009

Genetic researchers have revised an earlier hypothesis that members of the Jewish priestly caste, the Cohanim, can trace their paternal lineage to a single progenitor, perhaps the biblical Aaron, brother of Moses.
Jewish men who report such family lineage still share a remarkable set of similarities in the genetic makeup of their Y chromosomes, but further study by UA population geneticist Michael Hammer and a group of Israeli colleagues has now traced several lineages of the priestly caste to several unrelated men in the Near East more than 3,000 years ago.
"I think it's still sort of amazing that there is a genetic marker," said Rabbi Sam Cohon of Temple Emanu-El in Tucson.
"The question of whether it was one progenitor or was it four or five, it doesn't damage my faith in any way," Cohon said.
"The original idea was to test the idea of a single male lineage," said Hammer, director of the UA's Human Origins Genotyping Lab.
Hammer said the new research, while revising the initial conclusion, actually offers more evidence than before for the direct line of descent from a core of early priests who lived in the Near East in the time between the Exodus from Egypt and the dispersion of the Jews.
Hammer describes the Cohanim tradition as "a family heirloom passed from father to son."

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Background here.