Though I'm not sure how Abraham or Sarah were "Jewish" in the sense of Judeans or Judahites since Judah was yet born, I can perceive merit in considering why people ever felt the need to sacrifice anything even to idols and to consider the nature of the psychology behind it. Is it innate? Or is it systematically taught? Is it because of guilt or is it a means of avoiding guilt (speaking of a tendency or perhaps character and propensity toward blaming someone else)?
However, one thing I don't get is why they (Abraham and Sarah) would have would feel guilt about something that was acceptable in their society. Though possible they may have been siblings of different mothers.