Jewish Genetics

The fact that one’s genetic code is a combination of the DNA one inherits from both mother and father is a basic lesson of high school biology. According to traditional Jewish thought, one’s spiritual DNA is also derived from one’s biological background.

In Deuteronomy, the Torah strongly warns that one should not “give your daughter to his [a gentile’s] son, and you shall not take his daughter for your son, for he will cause your child to turn away from Me, and they will worship the gods of others” (Deuteronomy 7:3-4). The use of the ambiguous pronouns in this verse are clarified in the Talmud: “Rabbi Yochanan said on the authority of Rabbi Shimon bar Yochai, because Scripture says, ‘For he will turn away your son from following me:’ your son by an Israelite woman is called your son, but your son by a heathen is not called your son. Rabina said: This proves that your daughter’s son by a gentile is called your son” (Kiddushin 68b).

The Biblical passage cited above is regarded as the source for matrilineal descent, the Jewish legal principle that one is Jewish if one’s mother is Jewish (or if one converts). Thus it is written in the Book of Ezra (regarding the people who are preparing to return to Israel and rebuild the Temple): “We have broken faith with our God and have married foreign women of the peoples of the land…” (Ezra 10:2-3).

The father’s “spiritual genetic” contribution is equally important, although it’s importance was more tangible before the exile of the ten “lost” tribes. From one’s father, one inherits tribal affiliation. However, since the Assyrian conquest of the Northern Kingdom of Israel, the significance of this tribal designation is much more limited and is primarily used in determining whether one is a Kohain (priest), Levite or Israelite.