In humans, support from partners and alloparents is crucial for successful child-rearing and optimal child development. However, the complex relationships among childcare support, children's outcomes and parental characteristics have not been fully examined. We investigate how three sources of partner and alloparental support—partner's childcare participation, support from children's grandparents and support from non-kin—can be associated with child social development. We hypothesize that the associations between childcare support from partners/alloparents and child social development are partly mediated by parental psychological condition and parenting style. To test this, we conducted path analyses on online survey data collected in 2016 from parents of 3- to 5-year-old children in Japan. We found no evidence that childcare support had direct positive effects on child social development. Rather, the benefit of childcare support was mediated by its effects on parental psychological condition and parenting style, which in turn improved children's outcomes. At the same time, we found some evidence that greater availability of childcare support was directly associated with more behavioural difficulties in children. Our findings reveal the complex pathways between childcare support, parental characteristics and children's outcomes in Japan, showing potential mechanisms behind parental and alloparental effects in industrialized populations. This article is part of the theme issue ‘Multidisciplinary perspectives on social support and maternal–child health’.

Adolescence is identified as a key period for identity development, but anthropological literature hints at cross-cultural variations. Past research suggests Japanese adolescents may experience more identity exploration/confusion compared to Western counterparts, but the reasons behind these findings remain unclear. This comparative study investigates how adolescents in England and Japan perceive and engage with their environments, and aims to identify similarities/differences that could explain cross-cultural variations in identity development. Using autophotography, 98 teenagers aged 13 to 15 years across 10 schools in England and Japan documented important aspects of their lives. We applied template analysis to qualitatively analyze these photographs/texts. Overall, we identified two shared themes between countries: “This Is Me,” reflecting personal identity through self-discovery and skill development, and “Connectedness,” emphasizing relationships and belonging. A Japan-specific theme, “Reflections Through Time,” captured the broader temporal lens of Japanese adolescents, sometimes with a sense of melancholy. This notably differed from English adolescents in our study, who focused on the present in a positive manner. These findings suggest cultural differences in how adolescents engage with their environments, which may contribute to cross-cultural variations in identity development. Our findings point to the importance of biocultural approaches in developmental research by considering the role of culture.