I am taking a stab in the dark, but I think there might always be this size difference between these 2 cousins. Brigham thinks Jonah is awesome and continually tries to engage in play with him. Jonah on the other hand is scared of Brigham. Eventually they will play together.
The first book he read was "I like bugs". It was also the first book Ally read. The girls were more than willing to sit there as long as they could tell he was reading the actual words and not making it up.
Ben we are so proud of you! You've worked hard to learn how to read. We are glad you are excited about your new skill.