Levirate Marriage and the Family[ ]GEMARA
a. Our rabbis taught: Which [women] are [in the category of]
secondary relatives? His mother’s mother, and his father’s
mother, and the wife of his father’s father, and the wife of his
mother’s father, the wife of his father’s brother from the same
mother, and the wife of his mother’s brother from the same
father, and his son’s daughter-in-law, and his daughter’s
daughter-in-law.
b. A man is permitted to [marry] his father-in-law’s wife and his
stepson’s wife, but forbidden to [marry] his stepson’s daughter.
His stepson is permitted to [marry his stepfather’s] wife and
daughter....
c. It was asked of them: The wife of his mother’s brother from the
same mother, what is her status? [Is a distinction made between
her and] the wife of his father’s brother from the same mother
and the wife of his mother’s brother from the same father — [do
we say because] both involve a father, the rabbis made a decree
about them, but where there is no father involved, the rabbis
do not make a decree, or is there perhaps no distinction [and
the wife of the mother’s brother from the same mother is also
forbidden]?
d. R. Safra said: That [prohibition against the wife of his mother’s
brother from the same father] is itself a decree; do we make a
decree based on a decree!
e. Rava said: Are not all [the prohibitions regarding secondary
relatives] a decree based on a decree? His mother is forbidden
[by the Torah], his mother’s mother is a secondary prohibition,
and they decreed regarding his father’s mother because of
his mother’s mother. What is the reason [for this additional
prohibition]? All of them are called “the household of
grandmother.” His father’s wife is forbidden [by the Torah],
his father’s father’s wife is a secondary prohibition, and they
decreed regarding his mother’s father’s wife because of the
father’s father’s wife. What is the reason [for this additional
prohibition]? All of them are called “the household of
grandfather.” The wife of his father’s brother from the same
father is forbidden [by the Torah], the wife of his father’s brother