Attachment Bonds and Baby Booms: A Cross-Cultural Study of Reproductive Success.

The goal of the current study was to explore attachment theory and reproductive success across the three cultural contexts of Japan, Canada and the USA. We investigate how adult attachment styles (secure, fearful, preoccupied and dismissive) are associated with reproductive success, as measured by the number of children. Using data collected from 15,120 participants via an online survey, we found fearful and preoccupied attachment styles were positively associated with reproductive success across all three samples, indicating that these insecure attachment styles may promote behaviours linked to larger family sizes. Conversely, secure attachment negatively predicted reproductive success in Canada and the USA but showed no significant relationship in Japan. Sex differences in attachment were observed, with women scoring higher in preoccupied attachment across cultures and men scoring higher in fearful attachment. We propose attachment styles are associated with reproductive strategies, with cultural norms moderating these associations. Collectivist values in Japan may attenuate individual attachment associations with family planning, while individualistic cultures such as Canada and the USA align secure attachment with deliberate, resource-intensive reproductive strategies. This study advances the understanding of attachment theory by discussing its relevance to life history strategies and reproductive outcomes within diverse cultural settings.