Genealogical mixing and genetic mixing have little to do with each other - the pool is too diluted at these scales and there can be much local variation.
By the way, the fact that all of us share the exact same set of ancestors from a few thousand years ago isn't new, shocking or controversial, only the exact date is still subject do debate. You may find this link useful: https://en.wikipedia.org/wiki/Identical_ancestors_point
By the way, the fact that all of us share the exact same set of ancestors from a few thousand years ago isn't new, shocking or controversial, only the exact date is still subject do debate. You may find this link useful: https://en.wikipedia.org/wiki/Identical_ancestors_point