The eleventh perek of Massekhet Yevamot deals with out of the ordinary family connections and relationships. While most of them focus on relationships in the context of yibum (levirate marriage), which is, after all, the topic of this tractate, other relationships are dealt with, as well. One example that is discussed is based on the fact that some issurei erva – incestuous relationships – take effect only when the man and woman involved were married, and not if their sexual relationship took place outside of marriage. Thus, for example, the Tanna Kamma of the Mishna on our daf permits someone to marry a woman who his father had seduced or raped, even though that person would not have been allowed to marry her had she been his father’s wife.
While discussing these matters, the Gemara presents a series of odd family relationships that can take place under a variety of circumstances, most of which are identified as stemming from forbidden relationships. Examples include:
‘He is my brother and he is my son; I am the sister of this one, whom I carry on my shoulders’ — is possible when a gentile cohabited with his daughter. (The Gemara refers to a gentile because it does not wish to entertain the idea that a Jew would act in such a manner.)
‘Peace upon you my son; I am the daughter of your sister’ — is possible where a gentile cohabited with his daughter’s daughter.
‘Water-drawers, who draw water in buckets to irrigate fields, let this cryptic riddle fall among you: This boy whom I carry is my son, and I am the daughter of his brother.’ — This is possible where a gentile cohabited with the daughter of his son, as their son is also her uncle.
‘Woe, woe, for my brother who is my father, and who is my husband, and who is the son of my husband, and who is the husband of my mother, and I am the daughter of his wife; and he does not provide bread for his brothers, who are orphans, the sons of me, his daughter.’ — This is possible when a gentile cohabited with his mother and begot from her a daughter; then he cohabited with that daughter; and then the grandfather (his father) cohabited with her and begot from her sons.
‘You and I are siblings; your father and I are siblings; your mother and I are siblings.‘ — This is possible where a gentile cohabited with his mother and from her begot two daughters, and then he cohabited with one of these and begot from her a son. The son’s mother’s sister says this statement – she is his sister from his father’s side, his father’s sister from their mother’s side, and his mother’s sister from both sides.
It is not clear why the Gemara sees it appropriate to bring these, and other similar cases, since there seems to be no logical conclusion from them.
Rashi suggests that these were popular expressions – or riddles – of the times, and the Gemara chose to respond to them, even though there is no significant meaning to them. (Even today there are such expressions, like the popular song from the 1940s “I am my own grandpa.”)
The Meiri suggests that the Gemara brings these in order to poke fun at pagans, whose promiscuity could lead to such confusing family relationships.