Claim: Franz Xaver Wolfgang Mozart, nephew of Wolfgang Amadeus Mozart and Constanze Mozart, was born on July 26, 1791 and was also known as Wolfgang Amadeus Mozart, Jr.
Evidence: Franz Xaver Wolfgang Mozart (Wolfgang Amadeus Mozart, Jr.)
(1791-07-26)July 26, 1791
Vienna, Archduchy of Austria, Holy Roman Empire 
Franz Xaver Wolfgang Mozart (26 July 1791 – 29 July 1844), also known as Wolfgang Amadeus Mozart, Jr., was the youngest child of six born to Wolfgang Amadeus Mozart and his wife Constanze.