Abstract
With the worldwide increase in only-child families, it is crucial to understand the effects of growing up without siblings (GWS) on the adult brain, behaviour and the underlying pathways. Using the CHIMGEN cohort, we investigated the associations of GWS with adult brain structure, function, connectivity, cognition, personality and mental health, as well as the pathway from GWS to GWS-related growth environments to brain and to behaviour development, in 2,397 pairs of individuals with and without siblings well matched in covariates. We found associations linking GWS to higher language fibre integrity, lower motor fibre integrity, larger cerebellar volume, smaller cerebral volume and lower frontotemporal spontaneous brain activity. Contrary to the stereotypical impression of associations between GWS and problem behaviours, we found positive correlations of GWS with neurocognition and mental health. Despite direct effects, GWS affects most brain and behavioural outcomes through modifiable environments, such as socioeconomic status, maternal care and family support, suggesting targets for interventions to enhance children’s healthy growth.
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Data availability
The data supporting the findings of this study are divided into two categories: published data and restricted data. The voxel-wise neuroimaging statistical maps are available at https://figshare.com/articles/dataset/Voxelwise_difference/24716832 (ref. 87). The individual-level data are not openly available because access to these data must be approved by the Human Genetic Resources Administration, Ministry of Science and Technology of the People’s Republic of China. Individual-level data from samples are stored and kept in a server physically located in mainland China. They are available from the corresponding authors upon request and with permission from the Human Genetic Resources Administration, Ministry of Science and Technology of the People’s Republic of China.
Code availability
We made use of publicly available software and tools. The publicly available tools used in our analyses are described in Methods. The core codes are available at https://github.com/tj806345670/GWoS/tree/main.
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Acknowledgements
This work was funded by the National Natural Science Foundation of China (grant numbers 82430063 and 82030053 to C.Y., 82202093 to J.T., 82472052 to W.Q., 82371924 to J.X. and 82402218 to N.L.), Tianjin Key Medical Discipline (Specialty) Construction Project (grant number TJYXZDXK-001A to C.Y.), Tianjin Natural Science Foundation (grant number 19JCYBJC25100 to W.Q.), Tianjin Young Talents in Science and Technology (grant number QN20230336 to J.X.) and China Postdoctoral Science Foundation (grant number 2023M742623 to N.L.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
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C. Yu., J.T., Jing Zhang., Z.G., W. Li., W.Q. and M.W. designed the study. C. Yu., J.-H.G., Jiayuan Xu., Z.G., J.T. and W. Li. were the principal investigators. C. Yu., J.T., J.-H.G., Z.G. and Jing Zhang. wrote the paper. All authors critically reviewed the paper. J.T., J.-H.G., B.Z., Wenzhen Zhu., S.Q., G.C., Yunjun Y., W. Li., Hui Zhang., B.G., X.X., Y.Y., T.H., Z. Yan., Q.Z., F.L., M.L., S.W., Q.X., Jiayuan Xu., J.F., Y.J., N.L., P.Z., D.S., C.W., S.L., Z. Ye., F.C., W.S., M.W., D.W., Jiayuan Xu., Xiaochu Zhang., K. Xu., X.-N.Z., Long Jiang Zhang and Z. Yao. acquired the data. C. Yu., J.-H.G. and Z.G. supervised this work.
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Nature Human Behaviour thanks Toni Falbo, Charles Nelson, Jingxin Nie, Jing Yu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
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Tang, J., Zhang, J., Li, W. et al. How growing up without siblings affects the adult brain and behaviour in the CHIMGEN cohort. Nat Hum Behav 9, 1005–1022 (2025). https://doi.org/10.1038/s41562-025-02142-4
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DOI: https://doi.org/10.1038/s41562-025-02142-4
