Edmund is the "good" son, his parents' favorite – sensitive, smart, and shy. Jamie's the "bad" son, the bane of his parents' lives – dissolute, lazy, and rebellious. While Edmund has been nursed and worried over his entire life, the family gave up on Jamie long ago as a cause lost to alcohol and women.
Which is why it's fascinating, then, to see both brothers reciting poetry in the final scene. We see the sensitive, subtle side of Jamie even in the midst his blustering drunkenness, and we see the violent, capricious aspect of Edmund in his wild punches. The final act suggests, to us at least, that the brothers aren't really that different.