I nearly drove the car off Interstate Highway 35 when my grandfather told me, “I have discovered that our family might be related to Jesus of Nazareth.” I had been paying little attention to what Granddaddy had been saying, up to that point. We were nearing Selma, a tiny jurisdiction and notorious “speed trap” just north of the city limits of San Antonio, to which  I was driving my grandfather from Austin for an appointment with a medical specialist. Focused on making sure that I was under the speed limit, so that we would not be pulled over and shaken down for a huge fine, I had been ignoring my grandfather’s discussion of his latest genealogical researches. Tracing his ancestry had been his hobby since he had retired. A brilliant but half-mad engineer, he had concocted a fantasy genealogy for his ancestors that connected them with Scottish lairds and Norman barons. On the basis of dubious etymologies, like linking the French city of Rouen to the family name Hearon, he had persuaded …