Katherine Anne Porter to American frontiersman Daniel Boone and the writer O. Henry (whose real name was William Sydney Porter), her father's second cousin. In 1892, when Porter was two years old, her mother died two months after giving birth to her last child. Porter's father took his four surviving children (an older brother had died in infancy) to live with his mother, Catherine Ann Porter, in Kyle, Texas. The depth of her grandmother's influence can be inferred from Porter's later adoption of her name. Her grandmother died while taking eleven-year-old Callie to visit relatives in Marfa, Texas. After her grandmother's death, the
William Haldane Porter ceremony was conducted by her father Henry Cooke, at his own church in May Street Belfast. The couple almost immediately left for Palestine on their missionary work. Including William, there were 3 other children: Leslie Alexander Selim Porter (later Sir) (1853–1934) born in Damascus, who become Acting Governor General of the United Provinces of India until retirement to England in 1911; Norah Leslie Porter (1854–1934) born in Palestine, and Ellen Beresford Porter (known as Ela) (1864–1944) born in Belfast. Both daughters remained unmarried. Sir William was educated at Methodist College Belfast but may have been initially taught at home. At