LAUSR

Abstract A wealth of research has revealed that both sibling absence or presence and sibling relationship are essential contributors to children's theory of mind (ToM) skills. However, almost all these studies were conducted in Western, individualistic countries, and no study has yet focused on the sibling-ToM link in Chinese children. To address these gaps, firstly,113 children without siblings (Mage = 4.38 years, SD = 0.84, 53 boys) and 150 one-sibling children (Mage = 4.24 years, SD = 0.85, 64 boys) from China were compared by an established developmental ToM Scale. This study revealed that sibling status (e.g., children with a sibling vs without a sibling; children with an older or child-aged sibling vs. children with a young sibling) did not influence ToM scores. Moreover, for children with a sibling, positive interactions (but not negative interactions) between sibling dyads were positively associated with children's ToM skills. In conclusion, these findings suggested that the presence of one sibling at home only doesn't necessarily accelerate Chinese children's acquisition of ToM skills. It is the positive interaction between siblings that promotes the development of children's ToM skills.