LONDON (Reuters) - When it comes to American presidential elections, blue blood counts. So say British researchers who predict Democratic challenger John Kerry (news - web sites) will oust President Bush (news - web sites) on Nov. 2 simply because he boasts more royal connections than his Republican rival. After months of research into Kerry's ancestry, Burke's Peerage, experts on British aristocracy, reported Monday that the Vietnam war veteran is related to all the royal houses of Europe and can claim kinship with Czar Ivan "The Terrible," a previous Emperor of Byzantium and the Shahs of Persia. Burke's director...