Should my personal statement be about something academic, or should I tell a story about my life?

The topic you choose doesn't have to be academically related, and it's probably easier to reveal your personality (and those intangibles that don't already show up on your application elsewhere) by writing about a non-academic subject. However, that doesn't mean that the statement shouldn't be intellectual in the way you write about the subject. Your observations, descriptions, and conclusions will ideally reveal thoughtful insight and intelligence, though not necessarily in a direct manner (remember to show and not tell). An anecdote or story is always a great choice, but other formats can work too (though granted these are usually harder to pull off).