Purpose: Past research shows that parentally responsive behavior toward the child positively influences language development in both neurotypical children and children with intellectual and developmental disabilities, including those with fragile X syndrome (FXS); however, most studies have focused exclusively on the mother--child relationship.…

Research on factors underlying socioeconomic status (SES)-related inequalities in child development mainly focuses on single countries and specific influential factors. Only few studies scrutinize to what extent differences in children's early behavioural outcomes vary across countries and whether the processes that account for them are common or…