Insecure Attachment Linked to Larger Families Across Japan, Canada, and the United States

“Attachment Bonds and Baby Booms” surveyed 15,120 adults—5,040 from Japan, Canada, United States. Participants completed a questionnaire assessing secure, fearful, preoccupied, and dismissing attachment styles and reported children. Fearful and preoccupied styles were linked to fertility across countries; secure attachment correlated with fewer children in Canada, United States but not in Japan.

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Attachment theory holds that early experiences shape relational models influencing partnerships and parenting. Life-history theory proposes fast (more offspring, low investment) and slow (fewer offspring, high investment) strategies based on stability. Researchers hypothesized insecure attachment aligns with fast strategies, secure attachment with slow strategies, especially in individualistic cultures.

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Insecure attachment predicted higher fertility across the three nations; in Japan, fearful attachment showed the strongest link and secure attachment had no effect, which Fisher links to economic and cultural pressures. In Canada and United States, secure attachment correlated with smaller, planned families.

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In Canada and United States, women scored higher on preoccupied attachment and men on fearful attachment. In Japan, women scored higher on preoccupied, secure, and dismissing styles, while men scored highest on fearful attachment.

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Maryanne Fisher, Santamarian Research Chair, Saint Mary’s University, said the findings challenge view that secure attachment is optimal for reproductive success. She noted large sample detects modest effects and warned against equating statistical significance with practical importance, and stressed correlational design, noting attachment styles do not causally determine family size.

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The study relied on self-report data using an attachment measure, which may lack precision. Its design precludes causal inference, and focusing on WEIRD populations limits generalizability. Researchers noted unmeasured variables could affect both attachment and fertility.

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• “Attachment theory is one of the most influential frameworks in psychology, but discussions of it are often around emotional security and relationship quality rather than its generational consequences,” — Maryanne Fisher, Psychology Professor, Saint Mary’s University

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• “Essentially, the attachment styles usually labeled insecure (i.e., fearful and preoccupied), were linked to having more children, and the pattern held in all three countries,” — Maryanne Fisher, Santamarian Research Chair, Saint Mary’s University

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• “This means that the attachment styles we tend to judge as less desirable do not necessarily carry a reproductive cost,” — Maryanne Fisher, Santamarian Research Chair, Saint Mary’s University

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• “I have to admit, the divergence in Japan was interesting and really points to how cultural norms around family are influential,” — Maryanne Fisher, Santamarian Research Chair, Saint Mary’s University

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Future research aims to replicate the study in non-WEIRD populations and among individuals not using hormonal contraception, to examine how environmental factors interact with attachment across diverse fertility contexts.

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While insecure attachment consistently predicted higher fertility, the lack of a significant secure-attachment effect in Japan contrasts with North American findings, underscoring cultural modulation. The correlational design also leaves open whether attachment influences reproductive decisions or vice versa.

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