Firstly I have to state that, as he touches on in the program, genealogy is kind of bullshit.
Due to limitations of time and records, we can only focus on certain of the innumerable ancestors we have. Also, we pick and choose which ones are the "best" and just focus on them, forgetting that we have all the DNA from the uninteresting and unknown ones too. Also, how far back does it cease to matter? How related ARE you to that 14th century King of England, and, if you're prepared to count that, then you have just gained a million distant cousins who are also "heirs". Great. More family to dislike and ignore.
My grandfather's surname has been in the states for ever. Someone did a tremendous amount of research on them and I came across most of the findings a couple of years ago. The oldest record is in the 1680s, I think. I keep meaning to check if anyone came on any boats of note (Mayflower power) but something always distracts me, and I have to question that even that recently in history, does it matter? Following one surname through endless branches disqualifies thousands of other relatives. I still occasionally dabble partly because it's a great way to sharpen researching skills and partly because it does put a human face on history: yours.
Have I mentioned that I love Stephen Fry? I adore him. I love every second of him. I listen to him speaking when I'm at the gym, instead of music.