Truth is a disputatious concept in memoir. I’ve said that nonfiction shouldn’t involve invented characters or scenes, unless the author cues the reader to such imaginings, because readers understand the implicit promise in the genre to abjure sleight of hand. But “memory has its own story to tell,” Tobias Wolff argues in introducing This Boy’s Life, meaning that the subjective memories of which memoir is made are the truth. And memories are tumbled in our minds into creative reconstructions to …