In Jaap Robben’s “Summer Brother,” a 13-year-old finds himself the default caregiver for his severely disabled brother. His dad’s a swindler. The bills are due. Disaster is inevitable.In Jaap Robben’s “Summer Brother,” a 13-year-old finds himself the default caregiver for his severely disabled brother. His dad’s a swindler. The bills are due. Disaster is inevitable.Read MoreBooks and Literature, Summer Brother (Book), Robben, Jaap