# Unusual number of males among the 70 who went to Egypt

B'reshis chapter 46 lists the seventy descendants of Yaakov who went to Egypt. It actually lists sixty-nine: let's assume Yocheved was the seventieth, as Rashi explains. It also lists (in pasuk 12) two who died before the trip down, so there are a total of 72 descendants of Yaakov listed. Of these, three are female: Yocheved, Serach, and Dina. Assuming a 50% chance of having a boy at each birth, the probability of such a disproportionate number of babies of one sex is about 0.000000000000003%. What's going on?

(And if you want to say there were females not listed (besides Yocheved), then you have to explain why the Torah says there were seventy (do the females not count?) and why it lists some females and not others. That's even if, as suggested in an answer, there are dead females not listed: the Torah lists dead males, after all.)

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(See Rashi, Bemidbar 26:24) (relevant, but not an answer) – b a Jul 9 '12 at 23:00
@msh210 This is a simple way to calculate it on WolframAlpha: wolframalpha.com/input/?i=3+heads+in+72+coin+tosses (Though to be fair should add chance of 0-2 heads also, since that would be even more unusual.) – Ariel K Jul 11 '12 at 17:09
@ArielK, I did include the chances of 0 to 2 heads also, and doubled it to allow for 0 to 3 tails also. – msh210 Jul 11 '12 at 18:31
news.asiantown.net/r/29462/… – Seth J Apr 25 '13 at 0:50

This link discusses this question at length. http://www.etzion.org.il/vbm/archive/9-parsha/13vayigash.rtf

Rash"i mentions (to answer for the opinion that there were girls born along with each of the sons of Ya'akov) that there were more females but they all died before going to Egypt. However, we are left with the implication that only those named and counted were part of the descending party. (. . which entails that all of Ya'akov's sons married Egyptian women, making it not remarkable when an Israelite man married an Egyptian woman later in the Torah, among other technical difficulties!)

Perhaps the number 70 is used not [only] as a census, but as a qualitative description of Ya'akov’s family for the purpose of comparing it in its totality to the nations of the world, which also comprise 70. (cf. D’varim 32:8-9) The reason Rash"u et al. were compelled to give an explanation for the absence of many females was that the inclusion of Dina and Serach indicated that women were being counted, despite the general rule that only males are counted when the Torah records census data. The burden of explanation is really on the inclusion of these two women, not the exclusion of all the others.

Thus, an alternative [to the null hypothesis] to explain their inclusion could be that the Torah wanted to add up to exactly 70, while fitting the pattern of each wife - Le'a and Rachel - having exactly twice the number of offspring as her slave - Bilha and Zilpa. These specific members of the family were chosen from among all the other females due to their special merits, as attested in the midrashim.

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What's the problem? I know families with multiple generations of mostly (or all) boys. There's a family that comes to mind with something like 6 brothers who are mostly married, and there are now between 4 and 6 sons to each of those brothers. In all, the grandfather has about 24 or 25 grandchildren. If I'm not mistaken there is one granddaughter among them.

I also have family with similar rates.

It's not like it can't happen. It's just surprising, perhaps, if you live your life by statistics.

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This may be right (and +1), but it's unsatisfactory and something I should've mentioned in the question. Sure, no matter how unlikely the sex ratio, it appears sometimes; coming across such a family, it's certainly possible (and nowadays in the USA I'd say very likely) that it occurred by chance, and that's all. But if I came across it in China, I'd say the likelihood is greater that sex-selective abortions had been performed; likewise, for people under close hashgacha like Yaakov, there may be a better explanation than chance. – msh210 Jul 9 '12 at 6:58
No doubt it was part of HaShem's plan. But I would say the same thing for any family. Does that mean that it necessarily warranted the attention of a major commentary? Perhaps, but if not, I'm not concerned. – Seth J Jul 9 '12 at 12:55

Male vs female is not blind 50-50%, it depends on us too. As mentioned in Niddah 31a (last line), with some effort one can make his wife to born just boys. If you see further on 31b you can see such a phrase

``````אמר רב קטינה יכולני לעשות כל בני זכרים
``````

my translation: Rav Ktina told: I can make all my children to be boys.

If Rav Ktina could, I think that children of Yaakov also could make it.

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Sure. But any reason for them to do so? – msh210 Jul 9 '12 at 19:35
They wanted to "produce" `am yisroel`, I think boys are more suitable for this mission. As we see that Yaakov has 12 boys and just one girl. And even that single girl was born as a girl because Lea didn't wanted to embarrass her sister. – jutky Jul 9 '12 at 19:40
@jutky perhaps edit that in? – Double AA Jul 9 '12 at 19:42
@DoubleAA the question was about `disproportionate number of babies`, not the reasons to do so. What I wrote in answer is a correct thing with good citation. What I wrote in comment is a speculation, I don't feel comfortable adding it as part of an answer. – jutky Jul 9 '12 at 19:47
@jutky Fair enough. FTR I don't think it's problematic to include speculation like that as an addendum especially if it is labeled as such. Plus, the question was "What's going on?" so that could include a 'why' answer in addition to a 'what' anser. – Double AA Jul 9 '12 at 19:53

Recent genetic studies show that male offspring tend to follow their father's trends in their own offspring. In other words, if there are a large number of males in a family, those males in turn, go on to produce a larger proportion of males to females (and the converse is true). The conjecture is that the weighting of male/female sperm is passed on to male offspring.

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Interesting. Can you cite any of these studies for us? – Double AA Apr 28 '14 at 15:07
And there seems to be such a trend in this family. – msh210 Dec 18 '15 at 20:40