According to biblical accounts, after the Jewish exodus from Egypt, Moses' brother Aaron was selected as the first Cohen (priest, alt.: Kohain, Kohan, Cohen, Kohen, pl. "Kohanim" or "Cohanim"). The designation was also given to his sons, providing the basis for a firmly entrenched Jewish tradition in which a male Cohen bestows the status upon his children. A daughter of a Cohen can become a priest, but she cannot pass on the honor.
For several centuries, starting about 3,000 years ago when the First Temple of Jerusalem was built, the Cohanim played a leading role in the Jewish community. Today, rabbis have taken over as the teachers and authorities of Jewish religion and law. They acquire their place through religious training rather than through heredity.
The Cohanim still often play a special role in worship services, such as being the first to read from the Torah. They also may recite blessings at Jewish festivals.
The Y chromosome also passes solely from father to son, exactly like the Cohen status. Scientific studies
have found that the Cohanim indeed have some Y chromosome features distinct from other Jews, which supports the
oral tradition of father-to-son transmission of priestly status. Moreover, the Cohanim are descendants of one man,
and have a common set of genetic markers - a common haplotype - that of their common genetic ancestor,
With the help of mathematical models scientists estimate that this last common ancestor of the Cohanim lived at some time between 2,100 to 3,250 years ago - a time coinciding with the oral history describing Aaron and his descendant Cohanim.
For more than 90 percent of Cohanim today to share the same genetic markers after such a period of time is a testament to the devotion of the Cohanim wives over the years. Even a low of rate of infidelity would have dramatically lowered the percentage.
The Cohen Modal Haplotype is found among many Jewish populations of the world, including Ashkenazim, Sephardim, and the Bene Israel of India.
Lineage testing can trace your ancestry back to real existing people who carried that particular DNA type throughout prehistory until today.
To test for Cohanim ancestry, males should select the Y-DNA test. Women who want to track their Cohanim heritage can have a male relative on their father's side take the Y-DNA test.
Jewish descent is traditionally defined through the mother, for which the mtDNA test is needed. In fact, genetic studies indicate that about 3.5 million of today’s Ashkenazi Jews - 40 percent of the total Ashkenazi population - are descended from just four women. Those women apparently lived somewhere in Europe within the last 2,000 years, but not necessarily in the same place or even the same century
Both men and women can take the mtDNA test to trace their Jewish roots through their the maternal line.