He was the son of Samuel "John" Galton, a prominent member of the scientific Lunar Society, and the father of Francis Galton the eminent (if somewhat eccentric) Victorian scientist. He born in the area of Duddeston in Birmingham. Samuel Tertius, though less distinguished, was not an exception to the rule of scientific endeavour in his family.
Galton also inherited his father's considerable business interests and quickly set about making changes - discontinuing the family's armaments business in 1815. Though fascinated by economics (he wrote papers on the subject) Samuel preferred to be less 'hands-on' in the running of the business than his father and spent much of his time living off the revenue of his considerable estate.
Though brought up a Quaker, Samuel converted to the Church of England in 1807. In 1807 Galton married Violetta (Francis Anne Viollette) Darwin, one of the fourteen children of his father's old colleague and fellow Lunar Society member Erasmus Darwin. Many of the 'Lunar children' grew up together and there were several such marriages. They had four daughters and three sons: