The Haldane (Hadden, Halden) families originated in Scotland, perhaps from Roger de Hadden, the earliest ancestor found in written records. Joining this study will help determine if there were more than one Haldane progenitor or if, perhaps, there were several. It may also connect Hadden and Haldane family members separated in genealogy by phonetic spelling of the surname in the 19th century and earlier. Famous Haldanes include genetic scientist JBS Haldane, John Scott Haldane, Viscount Haldane, Elizabeth Sanderson Haldane, and many more involved in science, politics, philosophy, and other disciplines.