Why Are All US Presidents Related? BridgeAnne d’Avignon, aged 12, was doing genealogy research on her lineage when she decided to change the course and try to decipher the genealogy of the presidents of the United States. She discovers all presidents are related! In her thorough research which involved over 500,000 names through history, her aim was to find the ancestry of all US presidents and see if there was a ‘presidential Adam’ that connected all of them. To everybody’s surprise, she discovered that 42 of 43 US presidents trace back to a single person: John Lackland Plantagenet, King of