half-brethren

Thus Hernando, the second, was legitimate; Gonzalo and Juan were his illegitimate half-brethren, having the same father but a different mother; while Alcántara was a uterine brother to the three illegitimate Pizarros, having the same mother but a different father.

South American Fights and Fighters And Other Tales of Adventure Cyrus Townsend Brady 1890

World,” and be troubled by such little things as the deaths of a few thousand servants, or even of two of his numerous half-brethren, hard at least on a day like this when he had seen his desire over his enemies.

A Victor of Salamis William Stearns Davis 1903