Last week, a halachic institute in Jerusalem published a collection of rabbinic opinions ruling that it is scientifically possible to determine whether someone is a Jew based on a simple DNA test.

“Testing the Mitochondrial genome, which is transmitted exclusively through the female germ line, makes it possible to identify relatives,” Rabbi Yosef Carmel, the Rabbinical Dean of the Eretz Hemdah Institute for Advanced Jewish Studies, told the Israeli newspaper Makor Rishon. “If it can be proven that a Jane Doe is the offspring of a Jewish mother, her own offspring would also be recognized as Jews (from birth).”

As nearly half of all Ashkenazi Jews can trace their lineage, via a particular genetic mark, to four women who emigrated from the Middle East to Europe about a thousand years ago, chances, Rabbi Carmel continued, “are high, statistically speaking, that anyone able to prove that they are the offspring of those four mothers is Jewish according to halacha.”

To make sure that both the math and the biology behind the proposition work out, the institute enlisted Rabbi Professor Nathan Keller of Bar Ilan University, an expert on combinatorics, and Professor Karl Skorecki, who directs Medical and Research Development at the Rambam Health Care Campus.

The institute, said Carmel, began addressing this question after it was approached by an unnamed prominent European rabbi. The rabbi, Carmel recalled, was contacted by a woman “whose maternal grandmother was a Holocaust survivor who wanted nothing to do with Judaism because of the trauma of her youth. There were no documents attesting if the young woman was indeed Jewish, and the only way to go was genetic testing.”

For obvious reasons, there’s something unsettling about equating Judaism solely with genetics. On the other hand, if the new ruling is adopted by Israel’s chief rabbinate, it might free thousands of Jews, including many who emigrated from the Former Soviet Union, of the burdens of having to prove their Judaism by going through a lengthy conversion process. If other scientists and rabbis endorse the new ruling, the age-old question of who’s a Jew may soon be answered with an app.