The nation's first African-American president may be descended from America's first documented slave

[Confusious]

2. It's not huge

go back far enough, and we're all related whether it be a slave or royalty.

As an example:

Watching QI, it's a British quiz show. The host, Stephen Fry, says " I have excited news, someone here is related to Richard the lion hearted." Later in the show, you find out everyone is.

The reason is,

you have two parents, 4 grandparents, 8 great-grandparents, 16 great-great-grandparents, pretty soon you get to more people then could possibly be alive at the time.

If a generation is 20 years, and it was 1640, that would be 18 generations ago. That would be 262,144 g-g-g-g-g-g-g-g-g-g-g-g-g-g-g-g-g-grandparents.

In 1640, there were only 26,600 (estimated) people in the colonies.

I personally have have a grandfather from that time, John Edwards, who was an indentured servant living in the south.