1. He suggests that "B'nei Temurah" does not refer to children born from a
union where the man intended to have relations with one wife and instead had
relations with another wife. Rather, it refers to children born from a union
where the man intended to have relations with an *Ervah* but ended up with
his wife. He supports this assertion with the logic that having intention to
live with one wife and accidentally living with the other is not serious
enough to cause the children to be "rebels." If, on the other hand, the man
has intention to live with an Ervah, then it makes sense that his children
will have terrible Midos, since he had intention to do something that was
absolutely forbidden.
All of the other Rishonim, however, cite the Ra'avad's second explanation of
"B'nei Temurah," as follows.
2. The Ra'avad suggests further that before the Torah was given, the Avos
did not observe the "Dikdukei Mitzvos," the fine details of the Mitzvos.
What does the Ra'avad mean? We know that the Avos kept all the Mitzvos
before they were given (see Yoma 28b)!
It seems that the Ra'avad is saying that the Avos did not keep the minor
points of the Mitzvos, and therefore Yakov was not careful to find out
beyond any doubt who the wife was that he had just married. Since he did
nothing wrong, the child was not affected. Alternatively, the Ra'avad might
be saying, like the OR HA'CHAIM says in Parshas Vayechi, that since the Avos
were not commanded to fulfill the Mitzvos, the had the prerogative to
sacrifice the observance of the minor details of a Mitzvah for the sake of
greater considerations (in this case, Yakov did not want to cause Leah to be
embarrassed).
3. The MAGEN AVRAHAM (OC 240) writes that "B'nei Temurah" are born when a
man does not see the woman he is with and thus he mistakes her for a
different wife of his. Yakov Avinu, on the other hand, saw the bride and
intended to live with whom he saw, but he thought that she was Rachel and
not Leah. However, according to the explanation of the MEFARESH of "B'nei
Irbuvya," such an error should still produce children who are "B'nei
Irbuvya."
4. The CHIDA in BIRKEI YOSEF (OC 240) suggests that the child is affected
only if the father did something wrong at the time of conception (like the
Ran says, "Tzad Aveirah"). Yakov Avinu, though, did nothing wrong; he made
every effort to verify that this was the bride that he thought she was, but
all of his efforts did not help. Since it was beyond his control, the child
was not affected.
The Chida points out that this answers another question. According to the
ASARAH MA'AMAROS (Ma'amar Chakar Din 3:10), Yishai -- the father of David
ha'Melech -- Yishai had intentions to live with his maidservant, but the
maidservant switched places with Yishai's true wife, and David ha'Melech was
born from that union. In that case, too, David was not a "Ben Temurah,"
because Yishai had given Simanim to his maidservant, but she gave over the
Simanim to Yishai's wife. Since the circumstances were beyond Yishai's
control, the child was not affected.
5. The CHIDA there then cites an ancient manuscript that asks not only from
the conception of Reuven and David, but also from the children of Yehudah
and Tamar. When Yehudah had relations with Tamar, he was unaware of the
identity of the woman, and if so, their offspring should have been "B'nei
Temurah." (This might not be a question at all, though, since Yehudah
certainly had intentions to live with that woman; he just did not know her identity.) The manuscript answers that the reason none of these cases
produced "B'nei Temurah" was because the intentions of the *mother* at the
time of the conception of a child are more important and consequential than
the intentions of the father. In each of these cases, the woman certainly
knew who the man was. It was only the man who did not know who the woman
was.
(This approach cited by the Chida contrasts with the words of RABEINU
AVRAHAM MIN HA'HAR, who writes that the intentions of the *man* are more
important that the intentions of the woman. Rabeinu Avraham Min ha'Har says
that this is why the Torah gives the man the right to divorce his wife (and
does not give the wife the right to divorce her husband) -- because if he
wants to divorce his wife, it affects her children (who have not yet been
conceived) more than if she wants to divorce.)
(Although Reuven and David were certainly not "B'nei Temurah," perhaps it
was this "Shemetz" of Temurah involved in their conception, in that the
father did not know who the woman was, that caused both Reuven and David to
be accused of a "Shemetz" of an Aveirah of Arayos. The Asarah Ma'amaros adds
that it is because of this slight imperfection in the conception of Reuven
that caused him not to be able to receive a portion of Eretz Yisrael proper
but to receive instead his portion in Ever ha'Yarden.)