On a personal note, I would go back to Sparta, Ontario ca. 1853 to find out what happened to my gg-grandfather and his wife, and why their children (including my g-grandfather) were "taken in" by their aunt and uncle. I would find out much more about this uncle, Samuel Haight, not on the direct line of ancestry but apparently a fascinating and prominent citizen anyway.
On the big picture, I would solve all the big mysteries, i.e. who was Jack the Ripper-was he Eddy, son of the future Edward VI? What happened to Jimmy Hoffa? What happened to Dorothy Arnold? And what happened to Amelia Earheart? (ok, that's more than two, even
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