Castaño was born July 2, 1957, in Amalfi, a small village in the Antioquia Department in central Colombia. He was the sixth among twelve siblings of a family of farmers. When he was 12 years old he  dropped out from school to help his father on farming duties.
On July 2, 1957, Castaño was born in Amalfi, a small village within the Antioquia Department of central Colombia. His family consisted of twelve siblings who were farmers. At the age of twelve, he left school to help his father with agricultural tasks.