Santos was born on August 10, 1951, in Bogotá, Colombia. He is the son of Enrique Santos Castillo and his wife Clemencia Calderón Nieto, his brothers are: Enrique, Luis Fernando, and Felipe. The Santos family has been a well established and influential family since the mid-20th century; his great-great-grandaunt was María Antonia Santos Plata, a martyr of the Independence of Colombia, and his great-granduncle was Eduardo Santos Montejo, President of Colombia between 1938 and 1942, who acquired the national newspaper El Tiempo. From there, his family has been connected to the newspaper and influenced the political life of the country; Eduardo's brother, Enrique, grandfather of Juan Manuel, and editor in chief of El Tiempo, was known as "Calibán" to his readers, and his three sons, Enrique (Juan Manuel's father) and Hernando Santos Castillo, and Enrique Santos Molano were chief editor, director, and columnist respectively. Through his father's brother, Hernando, and his mother's sister, Elena, Juan Manuel is also first cousin on both sides to Francisco Santos Calderón, former Vice President of Colombia during the previous administration from 2002 to 2010.