“…Research data were collected from secondary sources, such as parent and teacher reports (Birenbaum et al, 1989;Davies, 1983;Gerhardt et al, 2012;Lähteenmäki, Huostila, Hinkka, & Salmi, 2002), instead of collecting data from the siblings themselves. In other studies, siblings were used as the control group and were not the primary focus of the study (Larcombe, Mott, & Hunt, 2002;Tao, Julianne, Guo, & Robert, 1998;Zebrack et al, 2002;Zebrack et al, 2004;Zebrack et al, 2007).…”