Answer
Erasmus is Francis Galton's maternal grandfather. Galton was born on February 16, 1822, to Frances Anne Violette and Samuel Tertius Galton. Frances Anne was the daughter of Erasmus Darwin, who was a physician, philosopher, and poet. Erasmus Darwin was married to Mary Howard, and they had several children, including Frances Anne. Therefore, Erasmus Darwin is Francis Galton's maternal grandfather.