Francisco Javier Arana Castro was born on 3 December 1905 in Villa Canales, Guatemala. His parents, Ángel María Arana and Margarita Castro, were from a lower-middle-class family. He had both Spanish and Indigenous heritage, and the latter trait was visually more prominent. He did not have a formal education, but he was relatively well read, and was described by his contemporaries as canny and intelligent, and as a charismatic and convivial person. He was described as a poor public speaker, but as a very persuasive man in intimate conversations. In 1946, during the Guatemalan Revolution, a staff member at the United States embassy described his politics as nationalist, as well as being slightly pro-American.