Tamar, whose story is embedded in the ancestor narratives of
Genesis, is the ancestress of much of the tribe of Judah and, in
particular, of the house of David. She is the daughter-in-law of
Judah, who acquires her for his firstborn son, Er. When Er dies,
Judah gives Tamar to his second son, Onan, who is to act as
levir, a surrogate for his dead brother who would beget a son to
continue Er’s lineage. In this way, Tamar too would be assured a
place in the family. Onan, however, would make a considerable
economic sacrifice. According to inheritance customs, the estate
of Judah, who had three sons, would be divided into four equal
parts, with the eldest son acquiring one half and the others one
fourth each. A child engendered for Er would inherit at least
one fourth and possibly one half (as the son of the firstborn).
If Er remained childless, then Judah’s estate would be divided
into three, with the eldest, most probably Onan, inheriting two
thirds. Onan opts to preserve his financial advantage and
interrupts c