In Genesis 48:5-6, Jacob tells Joseph he is adopting his sons, which is then formalized by symbolically placing them on his knees (v12; cf. 30:3,6). But why does he do this? My best guess is that it is somehow related to giving Joseph a double portion among his sons (v22); if he adopts Joseph's TWO sons, Joseph's descendants will end up having a double portion as having two tribes represented among the twelve in Canaan. Anyone have any thoughts on this? Incidentally, it seems Joseph does the same thing with his grand children (50:23).