“…Guerin and Gottfried (1994) similarly reported few sex differences in rank‐order and mean‐level personality traits during childhood, while Roberts and DelVecchio (2000) reported no significant sex difference for rank‐order personality consistency. However, according to other studies with children (e.g., activity: Maziade, Côté, Boudreault, Thivierge, & Boutin, 1986; hyperactivity: Carlson, Tamm, & Gaub, 1997; Rutter, Giller, & Hagell, 1998), mean‐level sex differences were expected. Rothbart (1986) reported no sex differences in personality during the first year of life, and called for longitudinal research that would identify the period at which boys and girls start to differ.…”