Original sentence: The first son of former Real Sociedad and FC Barcelona player Periko Alonso, Alonso grew up surrounded by football; he and his younger brother, Real Madrid midfielder Xabi Alonso, would go training with their father when he was playing for CE Sabadell FC
Edited sentence: The first son of former Real Sociedad and FC Barcelona player Periko Alonso, Alonso grew up surrounded by football; he and his younger brother, Liverpool and Real Madrid midfielder Xabi Alonso, who also played with Real Sociedad, would go training with their father when he was playing for CE Sabadell