Mark Twain three of his siblings survived childhood: Orion (1825–1897), Henry (1838–1858), and Pamela (1827–1904). His sister Margaret (1830–1839) died when Twain was three, and his brother Benjamin (1832–1842) died three years later. His brother Pleasant Hannibal (1828) died at three weeks of age. When he was four, Twain's family moved to Hannibal, Missouri, a port town on the Mississippi River that inspired the fictional town of St. Petersburg in "The Adventures of Tom Sawyer" and the "Adventures of Huckleberry Finn". Slavery was legal in Missouri at the time, and it became a theme in these writings. His father was an attorney
Mark Twain whatever is found in its company may be gambled on as being the petrified truth; how I have succeeded, it would not be modest in me to say. Twain's story about his pen name has been questioned by some with the suggestion that "mark twain" refers to a running bar tab that Twain would regularly incur while drinking at John Piper's saloon in Virginia City, Nevada. Samuel Clemens himself responded to this suggestion by saying, "Mark Twain was the nom de plume of one Captain Isaiah Sellers, who used to write river news over it for the New Orleans Picayune.