Does a Convert's First Jewish Son Inherit Double?

Rabbi Yochanan and Reish Lakish debate whether children fathered before conversion prevent a subsequent son from receiving a firstborn's double portion.

Fatherhood Before Entering the Covenant

The Torah grants a double portion of inheritance to a father's firstborn son. Scripture defines this heir as the father's "רֵאשִׁית אוֹנוֹ" (the first of his strength). The Gemara examines a gentile who fathered sons, converted to Judaism, and subsequently fathered a son with a Jewish wife.

The Sages ask whether this new son receives the double portion of a בכור לנחלה (firstborn for inheritance). The fundamental question is whether conversion erases prior fatherhood entirely or whether biological paternity remains legally significant regarding the father's vigor.

First of Strength Versus a Newborn

Rabbi Yochanan and Rabbi Shimon ben Lakish (Reish Lakish) dispute this case directly. Rabbi Yochanan rules that the father has no firstborn for inheritance. Because he previously fathered children, he already produced the first of his strength.

Reish Lakish disagrees and holds that the father does have a firstborn for inheritance. In his view, a convert is like a newborn child. Therefore, his previous family ties are severed, and his first Jewish child begins his lineage anew.

רַבִּי יוֹחָנָן אוֹמֵר: אֵין לוֹ בְּכוֹר לַנַּחֲלָה — דְּהָא הֲוָה לֵיהּ ״רֵאשִׁית אוֹנוֹ״, וְרַבִּי שִׁמְעוֹן בֶּן לָקִישׁ אוֹמֵר: יֵשׁ לוֹ בְּכוֹר לַנַּחֲלָה — גֵּר שֶׁנִּתְגַּיֵּיר כְּקָטָן שֶׁנּוֹלַד דָּמֵי.

Rabbi Yoḥanan says: He does not have a firstborn with regard to inheritance, as he already had 'the first of his strength.' And Rabbi Shimon ben Lakish says: He does have a firstborn with regard to inheritance, as a convert who converted is like a child just born. (Bekhorot 47a:2)

Procreation and Populating the World

The Gemara links this dispute to whether such a convert fulfilled פריה ורביה (procreation). Rabbi Yochanan rules that he fulfilled the obligation through the children born in his gentile state. By having children, he satisfied the divine purpose to settle the earth.

Reish Lakish maintains that he did not fulfill procreation. Consistent with his position, conversion erases his earlier parental status in halacha. Because he is like a newborn, he stands without any halachically recognized children.

רַבִּי יוֹחָנָן אָמַר: קִיֵּים — ״לֹא תֹהוּ בְרָאָהּ לָשֶׁבֶת יְצָרָהּ״, וְרַבִּי שִׁמְעוֹן בֶּן לָקִישׁ אָמַר: לֹא קִיֵּים פְּרִיָּה וּרְבִיָּה — גֵּר שֶׁנִּתְגַּיֵּיר כְּקָטָן שֶׁנּוֹלַד דָּמֵי.

Rabbi Yoḥanan says: He has fulfilled it, as 'He did not create it to be a waste; He formed it to be inhabited.' And Rabbi Shimon ben Lakish says: He has not fulfilled procreation, as a convert who converted is like a child just born. (Bekhorot 47a:3)

Defining the Inheritance of Gentiles

The Gemara notes that Reish Lakish might grant a double portion because gentiles are not subject to inheritance laws. Rashi explains this phrase to mean that converts do not inherit gentile fathers once they convert.

Tosafot disagrees, noting that Kiddushin proves gentiles do inherit their fathers by Torah law. Instead, Tosafot clarifies that gentiles lack the double-portion firstborn rule. Consequently, the father had no halachic firstborn status until he entered the Jewish people.

אלא לאו בני נחלה נינהו דקאמר הכא היינו תורת בכורה

Rather, 'they are not subject to inheritance' that is stated here means the law of the firstborn's portion. (Tosafot on Bekhorot 47a:4:1)

Resolving the Controversy and the Halacha

A baraita appears to challenge Rabbi Yochanan by stating explicitly that a convert has a firstborn for inheritance. The Gemara resolves this by attributing the baraita to Rabbi Yosei HaGelili. Rabbi Yosei HaGelili holds that only opening a womb in Israel creates firstborn status, and he extends that logic to the father.

The halacha is decided in accordance with Rabbi Yochanan. The Rambam rules in Hilkhot Nachalot (2:12) that a convert who had children as a gentile has no firstborn for inheritance. Because biological strength was already spent, the subsequent son cannot take a double portion.

A convert's first post-conversion son does not receive a double inheritance portion, because prior children already constituted the first of the father's strength.

Learn Bekhorot 47 on Super Daf