UK television has a series called 'Who Do You Think You Are?' which goes into the ancestry of 'celebrities' (described by someone [Jennifer Saunders?] as famous people crying in libraries). It often seems to involve the famous subjects getting emotional at the news that their ancestors died, as if they really thought their great-great-great grandparents were still around somewhere or just faded away without making a fuss.

I haven't seen an episode that included DNA searches. It would be an interesting addition, but I do wonder if the results might vary depending on who did the analysis.