See introductory post on this book, After the Apple by Naomi Harris Rosenblatt.
The author notes polygamy and the fact that this is a polygamous society a number of times throughout the book.
From chapter 1 when God creates one woman for Adam's partner, she writes, "Another point the Bible suggests is that monogamy is more rewarding than polygamy. God creates one, not multiple, companions for Adam. Anthropologists tell us that men are generally polygamously inclined in consequence of a genetic drive to procreate whenever the opportunity arises. Yet it seems to me that by creating just one woman for the sole man the story is telling us that monogamy is the preferred state and that men need to curb, tame, and control their instinctive sexual drive. Monogamous marriage has been referred to by the psychologist Ned Gaylin as 'the institution for civilizing' sexuality. The Bible suggests that human beings are most nurtured by deep and lasting emotional relationships and the more we put into a relationship the more we get out of it. Multiple or serial relationships dilute the intensity that a monogamous relationship can develop because it concentrates the emotional, sexual, and intellectual aspects of human beings into a single focus. Each time we read of a biblical polygamous family, we read of suffering and pain." (pg. 6)
In the chapter of Jacob with his wives Leah and Rachel -- "In this story the Bible demonstrates a preference for monogamy by detailing the miseries of polygamy. Polygamy is shown to encourage rivalry among multiple wives to gain the single husband's sexual and emotional attention, to have the most children, to receive the most kudos, and to gain the most favor for their children...Modern men may fantasize about a plethora of available women, but the Bible depicts polygamous men as forced to deal with the politics and rivalry among their wives and their children, a rivalry that often extends into the next generations. It offers the sobering suggestion that the husbands (such as Jacob with Rachel, Abraham with Sarah, and Elkanah with Hannah) endured unhappy domestic lives because they had to deal with the misery and suffering of many women..." (pg. 91)
Through the laws of their days, Leah and Rachel each owned a servant given to them by their father. And as permitted in their times, they could give their servants to their husband in order to have children through the servants. Thus Jacob not only dealt with the politics of sleeping with his own wives, but was told by those wives to sleep with their servants, Bilhah and Zilpah, in order to have more children for Jacob. (Rachel was barren at this time so Bilhah was the only way she could have children.) (pg. 97)
You'll also recall Sarah came up with the plan to have children through her servant Hagar since she was barren and she decided to take matters into her own hands and have children through Hagar. Of course that all backfired and got rather ugly.