There’s an undercurrent of hysteria that threatens to sink KIM POWERS’s memoir, THE HISTORY OF SWIMMING, though the melodramatics have honest roots in the town of McKinney and his classically dysfunctional family: a successfully suicidal mother, an alcoholic father, and a trio of gay brothers whose youngest is plagued by his own drug and alcohol demons. Eldest sib Porky decamps for Washington; Kim and his younger-by-minutes twin, Tim, find work in New York. The narration revolves around Tim’s sudden disappearance on the city streets, possibly because of an epic binge that has left him unconscious or dead. Prompted by a day-old voice message, Kim makes a frantic dash to his twin’s old Texas haunts, but he finds only echoes of Tim’s sober past and is left wallowing in guilt over his brother’s troubled present. The story, while genuinely tragic, would be better served if the tears and tantrums were doled out more sparingly.