In the summer of 1977, my half-brother Henry was living in Bloomington, Ind., having moved there a couple years earlier after his parents’ divorce and our father’s marriage to my mother. I was not yet born, but would be by the end of the summer, and I imagine Henry was spending that summer like most 13-year-old boys do: mowing the lawn, swimming at pools, and talking excitedly about music and movies with our other brother, Greg.