I just found something similar. I googled a pair of my friend's ancestors that I didn't have dates for, and the first generation on the first page I looked at was Angelina Jolie. Someone has put her entire family tree on the web, going back 16 generations.
So I ran through it, and found 7 couples that are in the tree I'm doing. And they are all from different branches, as obviously everybody "upstream" from a married couple are also ancestors.
So my friend and Angelina share at least 7 ancestral couples. And I'm only working on a very small part of the tree at the moment.
There weren't all that many Europeans in New France. They intermarried out of necessity.
Incidentally, Angelina Jolie's father is Jon Voigt. I didn't know that

Cheers,
China