How Every Person at Some Point Will Be Either an Ancestor of All Who Are Alive or Those Who Are Dead
by Lori Dorn from Laughing Squid on (#6WMS1)

Cameron Duke from MinuteEarth explained another family paradox that predicts that every person, at some point in history, will either be an ancestor to everyone who is alive or to those who are no longer living, due to historical genealogies.
Another Ancestor ParadoxThere is a point in human history where everyone alive at the time fits into one of two categories: Either they are the ancestor of nobody alive today, or they are an ancestor of everyone alive today because of how genealogy and genetic lineages work - and it is much more recent than you think.
Why Families That Go Back Many Generations Have Far Fewer Ancestors Than They Expected