Many years ago, like 40 or so-?, There was some documentary I was watching, don't remember exactly what it was about but I distinctly remember at the end, the host declared that no matter how far we go back, none of us are 'farther apart' than 22nd cousins...
Doing a little googling some guy claims that he and most Icelanders are "something like" the 28th cousin of Queen Elizabeth II, and that anyone who can document ancestry back to the prophet Mohamed may be 40th cousins to the queen...
? I have no idea
As for my lineage, I did some checking a few years ago, only got as far back as around the great-great-great grandparents times-- weirdest thing I found was that there must've been some boring times in those days, because the common theme I found was HUGE families- like 10 to 14 kids was about average! (My dad was one of 9, mom one of 5, [I'm one of 5] and it just went up from there!) Haven't done much research since...