John was born in 1693 and his baptism took place on February 24th, 1693 in North Nibley, Gloucester. John's father was Thomas Curnock and his mother was Mary Norris. His paternal grandparents were Thomas Curnock and Elizabeth. He had two brothers and a sister, and also a sibling of unknown gender, named Thomas, John, Joanne and Hestor. He was the second oldest of the five children.