The fact that certain assertions are made in historical documents does not make them historically true.  Lots of things have been written in ostensibly “historical” documents and yet are demonstrably false.  The “historical” evidence for Jesus’ marriage to Mary Magdalene is not non-existent, but it is very weak.  Only a few lines in two ancient documents (written, still, scores of years after the death of Jesus) attest to this, and the texts are hardly unequivocal on this point.  The “bookshelf” full of books that attest to the same historical claim (that Jesus was a father) is conveniently vague.  Certainly there are no ancient sources that attest to this claim.  Brown builds his case on a historical house of cards and then simply asserts that his tenuous, weakly-supported conclusions are established historical fact.  This is “history” at its worst.