The book of Genesis is a window into what cultures were like before the revelation of the Bible. One thing we see early on is the widespread practice of primogeniture--the eldest son inherited all the wealth, which is how they ensured the family kept its status and place in society. So the second or third son got nothing, or very little. Yet all through the Bible, when God chooses someone to work through, he chooses the younger sibling. He chooses Abel over Cain. He chooses Isaac over Ishmael. He chooses Jacob over Esau. He chooses David over all eleven of his older brothers. Time after time he chooses not the oldest, not the one the world expects and rewards. Never the one from Jerusalem, as it were, but always the one from Nazareth. Another ancient cultural tradition revealed in Genesis is that in those societies, women who had lots of children were extolled as heroic. If you had many children, that meant economic success, it meant military success, and of course it meant the odds of carrying on the family name were secure. So women who could not have children were shamed and stigmatized. Yet throughout the Bible, when God shows us how he works through a woman, he chooses the ones who cannot have children, and opens their wombs. These are despised women, but God chooses them over ones who are loved and blessed in the eyes of the world. He chooses Sarah, Abraham's wife; Rebecca, Isaac's wife; Samuel's mother, Hannah; and John's mother, Elizabeth. God always works through the men or the boys nobody wanted, through the women or girls nobody wanted.