“By you Israel will pronounce blessings, saying,
‘God make you as Ephraim and as Manasseh.’”
Thus he put Ephraim before Manasseh. Then Israel said to Joseph, “Behold, I am about to die, but God will be with you and will bring you again to the land of your fathers. Moreover, I have given to you rather than to your brothers one mountain slope that I took from the hand of the Amorites with my sword and with my bow.” Genesis 48:17-22
Jacob had been the second born child, yet he got the blessing of the first born. Tradition gives the blessing to the first born, but Jacob upended the tradition and sought the blessing for himself. When it was time for Jacob to marry Rachel, Laban ambushed him with tradition and slipped him the older sister in the dark. Now Jacob claims his grandsons as his own, and blesses them in the order if his choosing.
God also blesses the second birth. It is not enough to be a child of your parents. The blessing goes to those who have been born again, and they have been chosen.