I've never exactly been a big fan of polygamy. Call me or prude or what have you, but the idea of having more than one woman in my life kind of frightens me. Jacob's life gives us a glimpse of the complications that arise from having more than one wife. Instead of living happily ever after, all kinds of rivalries ensue, and one wife is jealous of the other wife for bearing children. It makes perfect sense, then, that Rachel would offer her servant to her husband in hopes of getting a child in such a manner, doesn't it?
There are some ideas that seem DOA to begin with, and offering your maidservant to your husband just seems like one of those to me. I'm not sure it even takes a lot of genius to figure that out. The problem is that these ladies were so caught up in the emotion of the moment, that rational thinking seems to have eluded them. I realize that Jacob's response was somewhat culture, too, but I'm not sure it takes much common sense to come to the conclusion that sleeping with your wife's servant could create some future problems.
I can't help but think that, if Jacob and his wives had just stopped to rationally think through the decisions they were making, things might have fared better in their family. The same is true for us. Very rarely have I not know the better of two choices; the challenge is having the courage and discipline to choose wisely.