How many people think that Mary Magdelene came to Europe with Jesus's child?

I recently re-watched the Da Vinci Code and I am curious what other people make of the theory that the descendents of Jesus walk the Earth due to Mary coming ashore many centuries ago. I find it intriquing but I tend to (as strictly a guess) put more credence in the theory that it was a story circulated to re-inforce the conciet that French Kings ruled because they were divine and by divine right.