Favoritism almost always causes problems, especially in a family. It was the source of much anger and bitterness that resulted in pain and suffering for the family of Jacob. His father-in-law tricked him by giving him Leah instead of Rachel. Jacob didn't want the sister, but took her anyway, and then married Rachel a week later.

That started a lifetime of jealousy and competition that was compounded by Leah having four sons when Rachel had none. It soon escalated until between the two wives, and their two maids, Jacob had twelve sons and one daughter.

it was a hot mix of anger, resentment and bitterness that spilled over onto the boys and lasted their whole lifetimes as well.