In medical school, I read about ?Herodotus prescribing sleeping on the left side for women if they wanted a son. The Ancient Greeks believed that maleness was determined by the right ovary, while the left ovary determined femaleness. *edit: http://jmg.bmj.com/content/22/3/164.short

I ask because in Euripides's Phoenissae, there is a prophecy for Laius that says “if [he] beget a son, that child shall slay [him]”. Could this have been perceived as an actual choice?