Jesus' Brother Bob

Our friend Marilyn is into geneology. She recently discovered that her great-grandfather, in 1903, wrote a book explaining why his family is directly descended from Jesus Christ. So we got to talking about The Da Vinci Code and Holy Blood, Holy Grail, etc., and I said (because Marilyn's family traces itself back to Charlemagne), "Well, supposedly Christ fathered the first of the Merovingian line, and the Merovingians were succeeded by the Carolingians, who were probably their descendents. And the first of the Carolingians was...Charlemagne! So maybe you are descended from Jesus Christ." 'Cause lots of Mediterranean Jews fake crucifixion and elope to France, right?