advance the alternative that a man should both pray to God and contain himself during the time of intercourse in order to allow his wife to"bring

DEVELOPING HALAKHIC ATTITUDES TO SEX PRESELECTION

forth seed" first.

This last piece of advice forms the core of the most substantive Talmudic tract on sex preselection. Niddah 31a-b offers the following insight:

Rabbi Isaac, citing Rabbi Ammi, stated: If the woman emits her seed first she bears a male child; if the man emits his seed first she bears a female child; for it is said,"If a woman emits and bears a man-child."[Leviticus 12:2] Our Rabbis taught: At first it used to be said that"if the woman emits her seed first she will bear a male, and if the man emits his semen first she will bear a female", but the Sages did not explain the reason, until Rabbi Zadok came and explained it:"These are the sons of Leah , whom she bore unto Jacob in Paddan-aram, with his daughter Dinah" [Genesis 46:15], Scripture thus ascribes the males to the females[i.e., sons of Leah ] and the females to the males [i.e., his daughter Dinah].

"And the sons of Ulam were mighty men of valour, archers; and had many sons, and sons' sons"[I Chronicles 8:40]. Now is it within the power of man to increase the number of"sons and sons' sons"? But the fact is that because they contained themselves during intercourse, in order that their wives should emit their seed first, so that their children shall be males, Scripture attributes to them the same merit as if they had themselves caused the increase of the number of their sons and sons' sons. This explains what Rabbi Kattina said,"I could make all my children to be males."