Once thought to be a sign of witchcraft, extra digits are actually the most common developmental abnormality found at birth. About two children in a thousand have extra fingers or toes.
They’re even more common among the Amish, probably due to the “founder effect” — because the original settlers were few, their genetic legacy is amplified among their descendants, and apparently one of them had an extra finger.
They’re actually in quite good company. Marilyn Monroe didn’t have extra digits, urban legends notwithstanding, but Anne Boleyn and Winston Churchill both did. And Atlanta Braves pitcher Antonio “The Octopus” Alfonseca was born with six fingers and six toes. I’d like to hear him play the piano.