All lateral cephalograms were taken in a standardized position in centric occlusion with the same device (copy of the Broadbent cephalometer). The position was stabilized with ear rods and nasal support to prevent variations in the head position. The focus‐coronal plane distance was 150 cm, and the film‐coronal plane distance was 9 cm,22 which resulted in a constant magnification factor of 6%. The patients were asked to refrain from swallowing during the radiological examination, with tongue posture subsequently assessed on the cephalograms to ascertain that no children swallowed during the radiographic examination. The films were digitally scanned using an Epson Expression 11000XL – Photo Scanner (Epson America, Inc, Long Beach, CA) at a resolution of 300 dpi and 16‐bit grayscale.
After anonymization of all documents with a unique code, the scanned radiographs were traced by two trained and calibrated persons (MHZ and SNP) using OnyxCeph™ (Image Instruments, Chemnitz, Germany). Seven widely used soft tissue measurements were made on the films of 98 siblings at two time points: N‐Sn‐Pog', Cotg‐Sn‐Ls, Pr‐Ls, LbSup_I_Sn‐Pog', LbInf_I_Sn‐Pog', Id‐Li and Sn‐Pr (ǁFH) (Figure1 ).
After anonymization of all documents with a unique code, the scanned radiographs were traced by two trained and calibrated persons (MHZ and SNP) using OnyxCeph™ (Image Instruments, Chemnitz, Germany). Seven widely used soft tissue measurements were made on the films of 98 siblings at two time points: N‐Sn‐Pog', Cotg‐Sn‐Ls, Pr‐Ls, LbSup_I_Sn‐Pog', LbInf_I_Sn‐Pog', Id‐Li and Sn‐Pr (ǁFH) (Figure