During his youth in Kiel, Sieloff aimed to become a boxer, having stood in the ring 25 times by the age of 14. When his family moved to Rottweil near Stuttgart and after visiting football games of VfB Stuttgart at Neckarstadion, Sieloff's interest however shifted from boxing to football.
While growing up in Kiel, Sieloff dreamed of becoming a boxer, having fought 25 times by the age of 14. After his family moved to Rottweil near Stuttgart and attended VfB Stuttgart games at Neckarstadion, Sieloff's passion shifted from boxing to football.