Hopkins was raised in an affluent, accomplished, middle-class Church of England family. His parents, Kate Smith (1821-1920) and Manley Hopkins (1818-1897), were married in 1843; Gerard was their first child. His siblings included: Cyril (1846-1932); Arthur, artist and illustrator (1847-1930); Milicent (1849-1946), who became an Anglican nun; Lionel (1854-1952), a Chinese scholar; Kate (1856-1933); Grace (1857-1945), a musician who encouraged her brother’s interests; and Everard (1860-1928), an illustrator. Felix, a fourth brother, died in infancy in 1852. Kate Hopkins fostered her children’s educational and artistic interests. Manley Hopkins, an insurance broker who eventually owned his own firm specializing in maritime insurance products, was the author of A Handbook of Average (1857; a guide to “adjusting” expenses and financial losses when a ship was damaged or wrecked) and A Manual of Marine Insurance (1867). He also dabbled in poetry and belles letters.
Manley Hopkins, Gerard's father, provided the sections on Welsh calculation methods and “spectral numbers” (the “mental visibility of numbers”), and mathematical observations woven throughout the text. As biographer Norman White observes, “it is difficult to say with certainly where Manley’s contributions ended and Gerard’s began” (Hopkins, A Literary Biography, 6).
The frontispiece by Arthur Hopkins is entitled: “He was disarmed and thrown upon the floor.”
Everard Hopkins’s illustration, facing page 34 is entitled, “The Introduction to the Princess.”