if your interested in the factual basis of the book, read some of the books out there meant to prove the points.
The Da Vinci Code(aka "the book") was a fictitious story, based on alot of facts. when writing a book that you need to keep the reader "hooked" into, filling it with the entire actual, factual lineage of the priory would have been a slow down in the book.
*SOME* books that Cite the book and have additional information on certain aspects can be found
HEREsome more on the facts in the book can be found:
HERE(on christs lineage in france & Priory of Sion)
HERE(Godess worship)
HERE(Priory of Sion-Google search)