If a pregnant divorced gentile woman marries a different man and then conceives another child of opposite gender through superfetation, are the twins considered only half-siblings and permitted to marry?

  • "half-siblings and permitted to marry" Can you source that? My (admittedly imperfect) memory is that the halfness has to go the other way.
    – Yishai
    Commented Aug 29, 2014 at 15:23
  • 2
    This question appears to be off-topic because it is about gentiles marrying - not Jews. Please edit and clarify.
    – DanF
    Commented Aug 29, 2014 at 16:19
  • @DanF Jews marrying would not be on topic...
    – Double AA
    Commented Aug 29, 2014 at 16:39
  • @Nbz On the subject. A posek I was once studying under told me about a woman he knew who had both ovaries cycling at the same time. This is exactly the situation needed for superfetation. He said she had an extremely hard time getting clean as far as nidda goes. But he also said it was only temporary, after her next pregnancy her body straightened out and went back to each ovary taking turns with the other.
    – user6591
    Commented Aug 29, 2014 at 17:47
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    @DanF Judaism has halachos for non-Jews as well. Commented Aug 31, 2014 at 1:58

1 Answer 1


Yichus for nonjews according to Jewish law follows the mother. See Rambam hilchos milachim umilchamos chapter 9 halacha 5. Therefore these children are complete siblings as far as we are concerned.

I would like to add for the sake of clarity however that even relationships that are allowed such as a father marrying a daughter are off limits due to the fact that the non-Jews already decided to distance themselves from forbidden arayos. This is what the gemara meant by saying Lot's intentions were for an aveira, see tosafos in maseches Nazir 23a.


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