The basic laws of Judaism apply to foreigners who live among us: the Torah obligates them to fast on Yom Kippur, refrain from work on Sabbath, and destroy leaven on Pesach. Likewise, they must not blaspheme. Thus, an Egyptian foreigner was liable under Jewish law because his offense had been gross, he lived among us, and he was somewhat connected to the Jewish people through his mother.

In rabbinical tradition, Jewishness is matrilineal while clan affiliation is patrilineal. This leaves an “interfaith” family without a clan and, consequently, with no land to settle in. The assumption that “interfaith” families settled in the land of the wife’s clan is impractical: she did not inherit the land and physically had no place to live in. Women went to live in their husband’s clan’s tents; the suggestion that a man moves into the home of his wife’s clan amounts to matriarchy, which is alien to the Jewish Bedouin mind. Such an arrangement for mixed families would put intermarried women at an advantage compared to their properly married sisters: an intermarried sister would have gotten a land plot while the one married to a Jew would not. The Torah cannot mean to prescribe such an unjust arrangement.

Sages accepted patrilineal descent for all other nations. Rashi cites Kiddushin 67b: “A son follows his father” to assert the originally patrilineal descent. Also, the Pharaoh ordered the killing of Jewish boys rather than girls when he sought to extinguish the people. Rabbis counter without much proof that Jewishness was patrilineal, as it was with other nations, until the law was given on Sinai. That contradicts their other doctrine that the forefathers observed the law before it was given to the entire people; never mind that the forefathers married pagans unreservedly.

In practice, Jewish women certainly married the strangers who settled in the Land of Israel and adopted Jewish customs. They lived in towns without inheriting land plots, or they rented them. If the male stranger (ger) observed Judaism, their children were Jewish, according to their father’s new religion. If the woman married a non-observant foreigner (toshav), their children obviously followed the father’s religion. To all practical purposes, Jewishness was patrilineal.

The Jews-by-father were frowned upon: Leviticus 25:45 distinguishes between “your brother” and “someone rooted in ger’s family.” The skeptical attitude is unsurprising: landless converts-gerim were likely to take off and leave Israel along with Judaism. After a few generations, the descendants of gerim fully assimilated and often attained significant positions in Jewish society.

In rabbinical Judaism, the entry into Jewishness is religious while the exit is biological. Religious conversion is required to enter the nation, but the children of baptized Jews are considered Jewish. A more consistent definition would be, “Children of somewhat Jewish families are Jewish.” A foreign woman who marries a Jew and casts her lot with the Israelis—her children are Jewish. The self-hating Peace Now Jews cannot impart the Jewish soul into their children.