Antonio Teixeira Carneiro was born on September 16, 1872, in Amarante, the part of the Kingdom of Portugal (currently Portugal) to a working-class family. His father was a merchant.
When Antonio was a seven-year-old child, his father left the family. Soon, his mother died. The boy was sent to the orphanage under the Santa Casa da Misericórdia. Carneiro had stayed there for eleven years.