The personality is familiar to us all: the sweet old aunt, the loving grandfather or the generous widow down the street, each of them unfailingly kind toward friends and family but given to flights of shocking prejudice when the conversation turns toward ethnic groups to which they don't belong. Often the response is a nervous laugh, a wan smile or a hasty effort to change the subject. We assume that old people are the products of less-enlightened times; they're unlikely to change; and their comments, however ugly, are largely innocuous. Now, though, in the midst of the nation's first presidential...