[ ]Mapping the FamilyWe also learn that some degrees of kinship are stronger than others.
A stepchild is treated like a relative in some instances, but the degree of
kinship that exists between a stepparent and stepchild is not equiva-
lent to that of a biological parent and child. Ego is forbidden to marry
his stepdaughter or the daughter of his stepson, just as he is forbidden
to have a sexual relationship with his own daughter or granddaughter
[B]. However, he would be permitted to marry his stepson’s wife if she
became a divorcée or widow; her status is not equivalent to that of Ego’s
son’s wife, who would be forbidden even if her marriage to Ego’s son
ended. In-laws are part of Ego’s family, but some of the prohibitions that
extend to various members of Ego’s family of origin do not extend to his
family by marriage.
Having determined what types of relatives are included in the cat-
egory of “secondary” kin, the Bavli [C] asks about female relatives who
have not yet been considered. The question revolves around the status
of the “wife of [Ego’s] mother’s brother from the same mother.” The
woman in question is the wife of Ego’s maternal uncle; the uncle and
Ego’s mother have a common mother but different fathers. The problem
raised by the Bavli stems from the rabbis’ understanding of various pro-
hibitions in the Torah. Leviticus explicitly prohibits a sexual relation-
ship between a man and his aunt, whether she is his father’s sister or
his mother’s sister.^115 It also prohibits a relationship between a man and
his father’s brother’s wife.^116 The Torah does not prohibit a relationship
between Ego and his mother’s brother’s wife; Rav Safra [D] understands
this prohibition as a post-biblical decree. Furthermore, unless specified,
the relationships prohibited by the Torah are assumed by the Bavli to
deal with cases when siblings — in this case, one of Ego’s parents and
a sibling of that parent — have a common father. That being the case,
the Bavli regards prohibitions against a union between Ego and the wife
of his father’s brother from the same mother as a rabbinic prohibition
rather than a biblical one. The relationship under consideration, a re-
lationship between Ego and the wife of his mother’s brother from the
same mother, seems too far removed from the Torah’s prohibition to be
a legitimate case for a decree.
Rav Safra’s question underscores the emphasis on patrilineal descent
and the role of patrilineage in determining a hierarchy of kinship. The
question is not whether Ego is related to his uncles; they are certainly