*spoilers* Question on central concept

So the central concept is that the Holy Grail is actually the descendants of Jesus and Mary's union. So they had a daughter. Now if you assume the daughter married someone and had kids and they had kids, this means there a huge number of descendants of Jesus.

However, this is just not implied in the movie. It almost sounds like they kept having only 1 child so it was easy to track.

But the gene pool is so diluted now that genetics will not reveal exact blood specs of Jesus.

Overall, the movie was a fun thriller based on some fantasy and shot well. The acting was good and I liked it for what it was. It's not an Oscar winner but a movie that can regale you.