“The head of Breslov spoke with me for quite a while and asked me about my family names,” Roth recalls. Two weeks later, she was handed a genealogy chart showing that she was descended from Rebbe Nachman and his great grandfather, the Ba’al Shem Tov, the father of Hasidism. She was also related to the first Lubavitcher Rebbe and founder of Chabad, Shneur Zalman of Liadi. Through these great rabbis, she was told, she was a descendant of King David. (..)

To find a unique chromosomal marker shared by men who believe they are descended from King David, it is necessary for two who don’t know they are related to each other to have matching chromosomal markers. “If I can find someone from Baghdad community, who is somewhere on the line of the exilarch, and a European Jew who has a similar claim, and these families haven’t had contact for hundreds of years, if these two men have the same Y chromosome, I would have to take that as very successful,” says Bennett Greenspan, president and CEO of Family Tree DNA, which has conducted some of the Davidic studies. Greenspan says he has found such a chromosomal match between descendants of different branches of the al-Hashimi family that claim descent from the founder of Islam, the Prophet Muhammad.