I learn today that there is a thing called the genetic isopoint, a point in time where anyone then alive who had any descendants at all must (at least statistically)  be an ancestor of everyone alive today. And apparently it's more recent than you might think, less than 15,000 years or so.

Which means, of course, that we're all a mixture of some sort.  No secret to me, since discovering some ancestors in Jamaica half a dozen generations back who included both slave-owners and enslaved Africans.