Continuity mistake: In the ending scene with Daniel and Eli, Daniel starts yelling at Eli as Eli is running down the bowling alley. As Daniel is throwing bowling balls at Eli, the first ball is thrown down the left lane, hits Eli in the foot and ends up in the right lane - no pins have fallen. The second ball is thrown down the left lane and is a gutter ball - again no pins have fallen. The third ball is thrown into the right lane, hits a bucket and presumably hits no pins. However, as Daniel is chasing Eli behind the bowling alley you can see that the left lane now shows only 2 pins still standing.
Answer: There is nothing in the film to suggest anything other than that they are brothers. Paul sells out his family, takes the money and goes away. It is only natural that they would not want to speak of him later on. Daniel on the other hand, keeps a certain track on Paul, especially since he also got into the oil business and became a minor competitor to Daniel.
Twotall