What Wren is Looking at Theory
My best guess is it is a DNA test that Renee got on him. Perhaps for a short time there was some semblance of a relationship between Wren and his grandparents, until it soured once Renee found the undeniable truth about his origins, distancing herself from him and his parents. Chances are that he is looking in an attic for pictures or clues as to who his real father was, and he stumbles upon this document stating that Andrew is his biological father. Just a random thought.