Are We All Related?

If you draw the usual family tree, you can potentially go back too far, where there are more people in your family tree than there were people on the planet at the time. Yeah, this family trees can't grow exponentially forever, and yes, some of our ancestor were related to each other. But that's no reason to panic.

(YouTube link)

The YouTube channel It's OK to Be Smart explain how human ancestry and DNA diversity really works.