When I was a kid, my Dad would take me to Heartbreak Hill, rain or shine, to watch the Boston Marathon. For our family, the race held special meaning, because our “Uncle Bill”—William J. Kennedy, my paternal grandfather’s uncle—had won the event in 1917.

Though he had been dead for eight years by the time I was born, we still cherished the legend of “Bricklayer Bill,” as he was known. The Kennedys had plied the mason’s trade since at least …