“D'oh!” That's what Homer, the bumbling patriarch on “The Simpsons,” exclaims when he messes up by miscalculating the apocalypse by 30 minutes or hiring the fugitive Babysitter Bandit to stay with Bart, Lisa and Maggie.

There's a little bit of Homer in all of us — his catchphrase is so popular, it made the Oxford English Dictionary in 2001. Even family historians, careful as we are, experience our share of “d'oh!” moments, as in, “D'oh! I ordered micro-film for the wrong court records!” or “D'oh! I just spent six months on someone else's family!”