The character of Ephraim is something of an enigma when we begin to think of the root reasons for his nastiness and his stern and vengeful disposition. There is nothing in the play that we are told that would help us to understand his background and the kind of person that he is and has become. The only clues we can glean from the play relate to the way in which he is a very religious man. For example, he constantly recites Bible passages and, in response to the tragedy in the play, says nothing more than "God's hard," perhaps reflecting his religious faith and trust in God's sovereignty.
I imagine therefore that Ephraim was raised himself by some extremely strict and religious parents that never brought him up to enjoy life and constantly quoted scripture themselves to explain how life is actually an extremely bleak and joyless place. He would have been brought up with a very strong work ethic and also unable to truly love or take joy in those around him. This would help to explain his excesses as a character.