The Gemara says that when two brothers who share the same mother
become Gerim, after they convert they may not marry each other's former
wives. The Rabanan prohibited them from marrying each other's wives as a
Gezeirah, lest people not realize that the laws of Gerim are different and
think that it is permitted to marry "Eshes Achiv," the wife of one's brother.
In contrast, when the two brothers share the same *father*, they *may* marry
each other's former wives.
RASHI explains that the reason for this difference is because no one will
mistake the two Gerim (who do not share the same mother) for two normal
brothers. Since they are Gerim, and were born to an Ovedes Koachavim, people
assume that they were permitted to marry each other's wives since they are
not really brothers, because it is known that an Ovedes Kochachim involves
herself in Z'nus, and thus it can be assumed that her sons were not born to
the same father.
The Mishnah states that when a child is born to a Ger and a Giyores, and the
child was conceived before the woman converted ("Horaso sh'Lo b'Kedushah"),
the sons born afterward do not do Yibum with the first brother's wife (and he
does not do Yibum with their wives). RASHI in the Mishnah explains that the
reason is because a Ger does not have familial ties to his father, as the
verse states, "Zirmas Susim Zirmasam" (Yechezkel 23:20), and thus the first
son is not considered to have the same father as his brothers have.
Why does Rashi offer two different reasons for why a Ger is not considered to
be related to his father -- Zirmas Susim, and the Z'nus of the mother?
In fact, Rashi's source for his comments in the Mishnah is the Gemara later
(98a). The Gemara says that even twins who converted have no obligation to do
Yibum for each other -- although they clearly had the same father, Z'nus or
not Z'nus -- because of Zirmas Susim. Why, then, does Rashi in the Gemara say
that the reason is because of the assumption of Z'nus? He should have said
the same reason that he gives in the Mishnah, that a Ger is considered to
have no familial ties!
The same question may be asked on Rashi earlier in Yevamos (42a, DH
v'Yiftor). The Gemara there says that if a Ger and Giyores who are married
convert together, they are obligated to separate for three months in order
that we should be able to determine whether the child born to them after
Gerus was conceived after the Gerus or before Gerus. Rashi there explains
that this separation period is necessary because if the child was conceived
before the Gerus, the child would be prohibited from doing Yibum for the
brothers born after the Gerus and he would not know it. He would be
prohibited because of the assumption that an Ovedes Kochachim is involved in
Z'nus and thus the child conceived before the Gerus has a different father
than the brothers conceived after the Gerus, even though they share the same
Why does Rashi give that reason for requiring the Ger and Giyores to
separate? Even if the woman was *not* involved in Z'nus and the child was
indeed conceived from her husband and not from another man, the child still
may not do Yibum for the brothers conceived after the Gerus. He is not
considered to be related to them through the father, because of "Zirmas Susim
Zirmasam!" (The MAHARSHA asks this question on Rashi on 42a and leaves it
unanswered, suggesting that "perhaps an erring Talmid inserted these words
into Rashi," to which the ARUCH LA'NER concurs.)
(b) Later in the Sugya, the Gemara tells us that when Gerim convert, even if
they are from the same mother, they are not considered related to each other
because "Ger sh'Nisgayer k'Katan sh'Nolad Dami" -- a Ger who converts is like
a newborn child.
If so, why does the Gemara (98a) and Rashi in the Mishnah say that the reason
a Ger is not considered related to his father is because of "Zirmas Susim
Zirmasam?" The Gemara and Rashi should have said that the Ger is not related
even to brothers from the same mother, because he is "k'Katan sh'Nolad Dami!"
(c) How can the Gemara say that a Nochri is not considered related to his
father's family because of "Zirmas Susim Zirmasam?" The Gemara earlier (62b)
clearly proves that a Nochri *is* considered related to his father (i.e.,
they have "Chayas")! Moreover, the Gemara in Kidushin (19b) says that
mid'Oraisa a Nochri inherits his father, which clearly shows that they are
related! (HAGAHOS MAHARSHAM, citing SHO'EL U'MESHIV 3:3:34)
(a) The ARUCH LA'NER and RAV SIMCHAH M'DESVA answer that when Rashi says, in
our Sugya, that brothers who share the same father are permitted to marry
each other's former wives (and the Rabanan did not prohibit them) because
they are probably not from the same father, Rashi is *not* explaining the
Halachic logic. Rather, Rashi is explaining *what people think*.
People do not realize that "Ger sh'Nisgayer k'Katan sh'Nolad Dami," so they
will wonder why a Ger can may marry his brother's former wife. Likewise, they
are not aware of the principle of "Zirmas Susim Zirmasam" and that the Torah
removes the familial ties of the Ger. How, then, will people justify the fact
that brothers who are Gerim are permitted to marry each other's wives when
they share the same father? It is because people will think that the reason
we permit them to each other's wives is because they do not really share the
In truth, though, the reason they are permitted to each other's wives is
because of "Katan sh'Nolad Dami," which permits them even if they have the
same mother. The Rabanan, however, prohibited Gerim with the same mother to
each other's wives because people do not realize that it is the principle of
"k'Katan sh'Nolad Dami" that permits them, and thus the people will
mistakenly permit a normal brother to marry his brother's wife.
This answer does not explain Rashi's comments earlier (42a), however, because
there Rashi is not discussing what people will think. There, he is discussing
the actual Halachic reason for requiring a three-month separation.
The NODA B'YEHUDAH (EH 1:23) suggests that Rashi might agree with the view
cited by the SHACH (YD 269:6) in the name of the NIMUKEI YOSEF (3b of the
pages of the Rif, DH d'Tanu Rabanan). The Nimukei Yosef says that if two
brothers who are Gerim were conceived before their mother's conversion
("Hora'asan sh'Lo b'Kedushah") and born after their mother's conversion
("Leidasan b'Kedushah"), then they are prohibited to marry each other's
wives, like the Beraisa says, because they share the same mother. But if one
brother was conceived before the mother's conversion, and the other brother
was conceived after her conversion, then they are not considered related and
are permitted to marry each other's wives. The logic behind this ruling seems
to be that since one of them was conceived before the Gerus and one after the
Gerus, it is as if they were born to different mothers (ARUCH LA'NER -- this
logic is mentioned by the Gemara here, as a Hava Amina).
Rashi earlier (42a) is describing the relationship between one child who was
conceived before Gerus, and another child who was conceived after Gerus.
However, according to the Shach, they are not related through the mother, and
therefore they cannot be Asur to each other's wives mid'Oraisa. When Rashi
there says that it is Asur for them to do Yibum, he must be referring to an
Rav Acha bar Yakov, though, holds that they are not Asur mid'Rabanan to marry
each other's wives when they share both the same mother and father (because
people look only at the father and not the mother, and they assume that they
have different fathers and are not really related). The only time that they
are Asur, then, is when they share *only* the same mother and not the same
father. That is why Rashi says there that they probably do not have the same
father because it is assumed that the Ovedes Kochavim is a Zonah. Since they
have the same mother but not the same father, it is Asur mid'Rabanan for them
to marry each other's wives, and they may not do Yibum.
There are a number of problems with the answer of the Noda b'Yehudah. First,
Rashi clearly disagrees with what the Shach quotes in the name of the Nimukei
Yosef. (See Rashi 97b, DH d'Af Al Gav; 98a, DH Nasa; and see RASHASH here.)
The Noda b'Yehudah himself notes this in DAGUL MERAVEVAH (YD ibid.). Indeed,
the Acharonim point out that all of the Rishonim in this Sugya, including the
Nimukei Yosef, concur with Rashi on this point. Therefore, it seems that the
Nimukei Yosef earlier (on 3b) did not really mean to say that two brothers
are not considered to have the same mother when one was conceived before the
mother's Gerus and one after her Gerus. (See YASHRESH YAKOV, ARUCH LA'NER)
Second, according to the logic of the Noda b'Yehudah, every time two Gerim
share the same mother and father, they should be prohibited to marry each
other's former wife, since we assume that they really do *not* have the same
father (due to Z'nus), and only share a mother. Yet Rav Acha bar Yakov says
that if they have the same father and mother, it *is* a reason to permit them
to each other's wives. For these reasons and others the Acharonim reject the
answer of the Noda b'Yehudah.
We may suggest another answer for the words of Rashi on 42a, but first let us
answer the second question that we asked on Rashi.
(b) Regarding why Rashi, and the Gemara, do not mention the reason of "Ger
sh'Nisgayer k'Katan sh'Nolad Dami," Rashi himself deals with this question
(98a, DH Ha d'Amur). Rashi asserts that "k'Katan sh'Nolad Dami" is applied
only to a person (a Nochri) who was born before his mother converted
("Leidaso sh'Lo b'Kedushah"), and after he was born he converted. If,
however, he was conceived before his mother's conversion but was born
afterward, then since he was born to a Jewish woman we do not say that he is
"k'Katan sh'Nolad Dami," like a newborn child with no parents. When the
Gemara (98a) says that Nochrim have no familial ties because of "Zirmas Susim
Zirmasam," the Gemara is referring to two twins who were both conceived
before the mother's conversion and were born after her conversion. Similarly,
in the Mishnah -- which is discussing a child who was conceived before his
mother's conversion and born after his mother's conversion -- Rashi gives the
reasoning of "Zirmas Susim Zirmasam" and not "k'Katan sh'Nolad Dami."
This is difficult to understand, because the Gemara earlier (78a) states that
if a pregnant Nochris immerses herself in a Mikvah for the sake of Gerus, the
Tevilah is effective for her unborn child as well. The Gemara says that this
is because the mother's body is not considered a Chatzitzah, an intervention,
between the Mikvah and the fetus (this is according to the opinion that "Ubar
Lav Yerech Imo," a fetus is not considered part of the mother's body). It
seems clear from this Gemara that the child himself is a Ger in his own
right, even when he is born *after* his mother's conversion! Why, then, does
Rashi assert that he is not like a "Katan sh'Nolah" in such a case?
Perhaps Rava in our Gemara is following his own view elsewhere. Rava holds
that "Ubar Yerech Imo" -- a fetus *is* considered part of the mother's body
(see TOSFOS 78a, DH Ela), and that is why he does not consider the child
himself to be a Ger when the child is born after the mother's conversion.
Alternatively, even though the child is considered a Ger, like the Gemara
there (78a) implies, he does not have the status of a "Katan sh'Nolad,"
because he was born to a woman who was Jewish at the time of his birth. His
status is based on his birth, and not on his conception, and at the time of
his birth he was already Jewish.
Perhaps we can take this one step further. Just like "Ger sh'Nisgayer k'Katan
sh'Nolah Dami" applies only when the child who later converted was both
conceived and born before his mother converted, the principle of "Zirmas
Susim Zirmasam" also applies only when the child's father was a Nochri at the
time of his *birth*. If the father converted together with the mother and at
the time the child was born the father was already Jewish, then perhaps we do
not apply the logic of "Zirmas Susim Zirmasam," since at the time of his
birth his father was Jewish.
If this is correct, it might explain why Rashi earlier (42a) writes that the
reason the two sons of the Gerim would be prohibited to each other's wives is
only because the child that was conceived before Gerus might have been
conceived from a different father. "Zirmas Susim Zirmasam" will not apply
because his father converted before his birth! Therefore, the only Isur to
each other's wives is an Isur because of a Safek that the first son might
have been conceived by a different father, and thus they are not eligible for
Yibum. (This logic cannot be used to l'Kula, to *permit* brothers who are
Gerim to each other's wives by assuming that they are not related, because we
only consider it *possible* (i.e. l'Chumra) that they have different fathers.
We do not know *for sure* that their fathers are different. That is why the
Gemara normally uses the logic of "Zirmas Susim Zirmasam" to permit brothers
who share the same father to each other's wives.)
What we have outlined above describes Rashi's approach to the difference
between "Zirmas Susim Zirmasam" and "Ger sh'Nisgayer k'Katan sh'Nolad Dami."
However, Tosfos seems to have had an entirely different approach to the
TOSFOS in Bechoros (46a, Dh Nisgairah) says that the only reason Gerim are
not considered related to each other is because of "Ger sh'Nisgayer k'Katan
sh'Nolad Dami" and not because of "Zirmas Susim Zirmasam." Tosfos says that
"Zirmas Susim Zirmasam" is merely used by the Gemara to explain what people
*think* (the same way Rashi uses the logic of Z'nus). That is, the Rabanan
did not prohibit two brothers who converted from marrying each other's wives,
because people will not confuse those two brothers who are Gerim with normal
Jewish brothers. They will realize that the Gerim are *not* like brothers who
were born Jewish because of "Zirmas Susim Zirmasam." (The logic that an
Ovedes Kochavim is assumed to be involved in Z'nus is not mentioned
altogether by Tosfos.)
(c) We asked how the Gemara can say that "Zirmas Susim Zirmasam" teaches that
a Nochri is not considered to have Halachic familial ties, while the Gemara
earlier (42a) proves that a Nochri *is* considered related to his family
According to Tosfos in Bechoros, as cited above, "Zirmas Susim Zirmasam" is
not a true Halachic argument, but rather it is merely what people think to
themselves when they justify how Gerim from the same father can marry each
other's wives. Indeed, Tosfos brings the Gemara (62b) which says that Nochrim
are related to their fathers as proof against Rashi who says that "Zirmas
Susim Zirmasam" makes them not related, for we see that they are indeed
considered related even before they convert.
According to Rashi, we can offer two answers to our question. First, it could
be that Rashi holds that there is a difference between the relationship
between Gerim from the same father with regard to an Isur Ervah (such as
marrying each other's wives), and their relationship with regard to all other
matters (such as inheritance and Piryah v'Rivyah).
Alternatively, it could be that Rashi holds that "Zirmas Susim Zirmasam" is
only applied in a relative sense, when comparing a Ger to a Yisrael. But
while the two brothers are Nochrim and have not converted, they are certainly
considered fully related to each other. Only when comparing someone conceived
from a Nochri to someone who is presently a Jew do we apply the principle of
"Zirmas Susim Zirmasam." If this is true, Rashi is following his opinion on
42a (as described above, end of answer (b)), in which he explains that Zirmas
Susim simply means a Jew cannot be directly related to a Nochri. For this
reason, if the father becomes a Ger before his child is born, they are
indeed considered to be related and Zirmas Susim does not apply.
We must still ask, even if Zirmas Susim does not apply, why shouldn't we say,
according to Rashi, that a Nochri is not related to his father because we do
not really know who his true father is, as Rashi said on 42a?
However the answer to this is clear. The Torah does know who is whose true
son, so it could write "Bal'adan ben Bal'adan." When the Gemara discusses
whether a Ger who had children before Gerus must have new children after
Gerus, it is apparently discussing a situation where the father knows for
certain that the children are his. (For instance, he is confident that his
wife was faithful, or he and his wife were locked in prison together, in
which case he can assume the son is his based on "Rov," see Chulin 11b). With
regard to inheriting his father, even if the man who raised him is not his
true father, there is nobody else who has as strong a claim to the
inheritance as the purported son does, so he inherits his purported father
before anybody else.