Jacob favored his son Joseph over his other brothers and gave him a fancy coat. Joseph bragged about his dreaming of his brothers and parents bowing down to him. Joseph's brothers sold him into slavery, ripped his fancy coat, covered it in blood and let their father believe Joseph was dead. Joseph's brother Judah impregnates his daughter-in-law...but that is a story for another day. Joseph became successful while working for Potiphar but Potiphar's wife had the hots for Joseph so Joseph ended up getting thrown into prison. Joseph is eventually freed through interpreting dreams for the baker, cup bearer and Pharaoh. Pharaoh put Joseph in charge and there was a great famine. Only Egypt had food and it was under control of Joseph. Joseph's brothers came and bought food from Joseph but didn't recognized him. Joseph worked it out to get his whole family to Egypt, they were given choice land and everyone lived happily ever after...sort of.
Whew. Ten chapters in ten (sometimes run-on) sentences.
Jacob starts to near death and so Joseph brings his sons to Jacob (aka Israel) to be blessed by him:
Now it is important to know that Manasseh is the older of the two and therefore was to be given the better blessing which would be signified by placing the right hand on his head. But Jacob had a different idea:
"And Joseph took them both, Ephraim in his right hand toward Israel's left hand, and Manasseh in his left hand toward Israel's right hand, and brought them near him."
It is clear that Jacob purposely gave the better blessing to Ephraim by crossing his hands. It wasn't a simple mistake of grabbing the wrong boy's head. Jacob even says as much when Joseph confronts him over it. It is almost the same thing that caused all the problems between Jacob and Esau. Jacob was the younger brother and stole his older brother Esau's blessing. But in this situation the blessing of the younger son was intentional.
"And Israel stretched out his right hand and laid it on the head of Ephraim, who was the younger, and his left hand on the head of Manasseh, crossing his hands (for Manasseh was the firstborn)."
What I find interesting is that Joseph was a beneficiary of preferential treatment. He was treated by Jacob as if he was a first born child even when he was not. Yet he objects to Jacob treating Ephraim as the first born over Manasseh. It is an instance of where Joseph was willing to accept the preferential treatment when he was younger but then saw it differently when he was older. It is a cautionary tale of how our perspectives may change as we mature. It is also a good example of how patterns in a family tend to repeat.