There are two crazy things in this paragraph.  First, there is the matter of the “powerful House of Benjamin.”  Brown refers to the “House of Benjamin” (rather than the tribe of Benjamin) as if this were well-known entity and as if this were something akin to a powerful family like the Italian Renaissance “House of Medici.”  This is just wrong.  Originally Benjamin denoted a tribe within Israel, one of the twelve tribes that each occupied a different part of the land.  Eventually the tribal distinctions and tribal loyalties disappeared, as a centralized government was established to replace the old tribal confederacy, and people began to think more in terms of national identity than tribal identity.  But even if it were the case that people still cared a lot about their tribe in Jesus’ time, the tribe of Benjamin was not powerful, and it had not been for centuries.  According to the book of Judges (chs. 19-21), the tribe of Benjamin was decimated in a war with the other eleven tribes.  This war broke out when certain men from the tribe of Benjamin raped a woman to death and the tribe then refused to turn them over to face justice.  So many Benjaminites were killed in the subsequent war that drastic (and morally repugnant) steps were required to attempt to re-populate the tribe.   This hardly suggests that the tribe of Benjamin was particularly powerful, and there is no evidence in the Old Testament that the tribe’s fortunes ever were reversed.   Indeed, when Saul is chosen as the first king, his membership in the weakest of the tribes is probably a factor, many biblical historians argue, because many Israelites resisted the idea of a king precisely because they feared a single king from a powerful tribe would be likely to favor his own tribe and oppress the others.

The other crazy thing in this paragraph is the idea that a marriage between a member of the tribe of Judah (which Jesus supposedly was) and a member of the tribe of Benjamin (which Mary Magdalene supposedly was) would somehow be an earth-shaking event  that all Jews from Palestine to France would take note of, the “fusing” of two royal bloodlines, creating a “potent political union.”  This is just insane.  Does Brown expect us to believe that this is the first time a member of the tribe of Judah (even one who descends from David) and a member of the tribe of Benjamin have gotten married?  Inter-tribal marriage had been a common practice for centuries before the time of Christ; lots of people from the tribe of Judah married into the tribe of Benjamin and vice-versa.  Any real tribal boundaries more or less disintegrated after the time of Solomon.  What then makes this particular union so special?

Finally, it is ironic that after disparaging the reliability of the canonical gospels again and again, Brown assumes the reliability of these gospels when it suits him.  Notice here that he relies on the gospel of Matthew for his claim that Jesus was of the house of David.  This becomes even more ironic when one realizes that the genealogies of Jesus in the gospels of Matthew and Luke (which contradict each other again and again) are generally regarded by biblical scholars as among the least reliable parts of the canonical gospels.