A Reciprocal and Dynamic Development Model for the Effects of Siblings on Children's Theory of Mind

Siblings, shopping, and sustainability: Birth-order differences in green consumption

Several studies have examined the role of birth order in shaping human personality, but fewer have tested this variable in relation to other pressing issues. We conducted a birth-order study on green consumption, which enabled us to detect a small-to-moderate effect size equivalent to r = 0.15 or d = 0.30 with sufficient statistical power (N = 335). To capture green consumption, participants indicated their tendency to express the value of environmental protection through purchases and consumption behaviors. Firstborns (vs. laterborns) consistently expressed lower concerns linked to environmental protection in their purchase patterns. While the effect size of this finding was small-to-moderate by conventional standards and in direct contrast to the findings from a recent article on the same topic, these results could still be informative to address challenges associated with climate change considering the number of individuals with siblings in the world and the ease with which birth-order data can be collected.

The sibling effect on neurodevelopment of preschoolers under China's newly relaxed child policy: A national retrospective cohort study

Introduction

The change in Chinese fertility policy brings new challenges and considerations for children's health outcomes; however, very little is known about the interaction between siblings, family socioeconomic status (SES), and neurodevelopment in the Chinese preschool-age population. Therefore, this study aimed to develop a new explanatory pathway from sibling effect to early childhood development and explored the mediation effect of family SES in the pathway.

Methods

From April 2018 to December 2019, we conducted a national retrospective cohort study in 551 cities in China, and a total of 115,915 preschool-aged children were selected for the final analysis. Children's neurodevelopment, including Communication, Gross motor, Fine motor, Problem-solving, and Personal-social, was assessed with the Ages & Stages Questionnaires, Third Edition (ASQ-3). Hypothesis tests and multilevel regression models were used to assess the associations and their strength between sibling effect and neurodevelopmental delay. Pathway analysis was used to verify the mediation effect of SES.

Results

The results showed that there were significant risk effects of a sibling on preschoolers' overall neurodevelopment including communication, gross motor, fine motor, and problem-solving delay. The adjustment of family SES, however, brought a reversal of this association. The results of the mediation model illustrated a direct, protective effect of one-sibling status (βASQ-delay = -0.09; βASQ-scores = 0.07; p < 0.001), and an indirect, risk effect from one-sibling status through family SES to neurodevelopment outcomes (βASQ-delay =0.12; βASQ-scores = -0.12; p < 0.001). The total sibling effect was weakened but remained negative (βASQ-delay =0.03; βASQ-scores = -0.05; p < 0.001).

Discussion

This study concluded that family SES mediated the negative effects of one sibling on early child development. To enhance the positive influence of sibling addition, we suggested providing more resources and instructions to the families with less educated and poorer employed parents under the coming multi-child era.

A Closer Look at the Birth Order Effect on Early Cognitive and School Readiness Development in Diverse Contexts

Using the Early Childhood Longitudinal Study–Birth Cohort data, we examined the effect of birth order (firstborn vs. later-born) on children's cognitive skills at 24 months and school readiness (i.e., math and literacy) skills at age 4 years. Previous research in the U.S. using predominantly English-speaking, low-risk samples suggests that firstborns tend to show better early cognitive and school readiness skills than later-born children. However, results of the current study showed that although there was a firstborn advantage in low-risk or English-speaking families, in high-risk or language minority families, later-born children showed equivalent or even better skills than firstborn children. Our moderated mediation models revealed that children's engagement in home learning activities mediated the relation between birth order and developmental outcomes, and families' cumulative risks and language minority status moderated the mediation pathways. These findings underscore the complex associations between birth order and early development in diverse ecological contexts.