Bucknell Professor's Study Links Insecure Attachment Styles to Larger Family Size Across Cultures

Bucknell University Professor T. Joel Wade, psychology, is a co-author of a new international study examining how adult attachment styles relate to reproductive success, finding that individuals with certain insecure attachment patterns tend to have more children across cultures.

The study, published April 30 in the International Journal of Psychology, analyzed survey data from 15,120 participants in the United States, Canada and Japan. Led by Professor of Psychology Maryanne Fisher of Saint Mary's University in Halifax, Nova Scotia, the research team included eight authors representing all three countries.

Across all samples, the researchers found that fearful and preoccupied attachment styles — characterized by anxiety about relationships, fear of abandonment and relational ambivalence — were positively associated with having more children. The findings suggest these insecure attachment styles may promote behaviors linked to larger family sizes.

Wade, whose research focuses on evolutionary social psychology and human relationships, said the study highlights how psychological traits and cultural context shape family formation.

"The study shows that attachment plays a role in reproductive decision-making — or family size decisions," Wade says. "In every country, these more anxious attachment styles are associated with a higher number of children."

The findings align with life history theory, which examines how individuals allocate time and resources toward relationships and reproduction. In the study, secure attachment — typically associated with stable relationships — was linked to having fewer children in the United States and Canada, suggesting a more deliberate, resource-intensive approach to parenting.

"More secure people tend to communicate and work through relationship issues and may not feel the same urgency to have children quickly," Wade says.

In contrast, fearful and preoccupied attachment styles were consistently associated with higher numbers of children across all three countries, reflecting what researchers describe as faster reproductive strategies tied to relationship insecurity and dependency.

"They feel they’re going to be alone, so they may attach strongly," Wade says. "Having a larger family may serve, in part, as a kind of compensation for that fear of attachment."

Participants also reported how many children they would ideally like to have, and those preferences closely aligned with actual family size. Individuals with insecure attachment styles tended to both want and have more children, while secure attachment was associated with smaller desired and actual family sizes.

The cross-cultural design revealed differences among countries. In Japan, where collectivist values and concerns about population decline shape family decisions, the relationship between secure attachment and the number of children was not significant, suggesting broader social and economic factors may outweigh individual traits. Fearful attachment, however, remained positively associated with having more children, and in some cases more strongly than in the United States and Canada.

"In Japan, there is significant concern about declining birth rates, which is one reason for studying what influences reproductive decisions," Wade says. "This research shows how culture plays a role alongside psychology."

The study also identified sex differences consistent with cultural norms. In the United States and Canada, women were more likely to report preoccupied attachment, while men more often reported fearful attachment, reflecting differences in how relational dependence and emotional restraint are expressed.

Overall, the findings suggest that insecure attachment styles may confer certain reproductive advantages in specific contexts, challenging the assumption that secure attachment is always the most adaptive pattern.

"Attachment styles, culture and sex all work together in shaping reproductive outcomes," Wade says.

The study is part of an ongoing international research effort, with researchers continuing to expand the dataset to better understand how personality and cultural factors influence decisions about having children over time.