“…By contrast, co-twin independence appears to be associated at school with girl-boy pairs. This result is in line with the idea that mixed-sex twins are differentiated the most by their parents since early childhood, as demonstrated in several studies on dress practices (Brooks & Lewis, 1974;Goshen-Gottstein, 1981;Robin, Josse, Kheroua, Casati, & Tourette, 1994). Moreover, some studies have shown that already by preschool age, friendships are formed on the basis of sex identification (La Freniere, Strayer, & Gauthier, 1984).…”