Study finds unpredictable childhood environments are linked to borderline personality traits in adulthood - PsyPost

What the report says

PsyPost reported that a study published in Evolutionary Psychological Science links adults’ memories of unstable childhood environments with higher levels of borderline personality traits. The article, published July 20, 2026, says the research examined borderline-related features as traits across the population, including emotional volatility, interpersonal conflict, impulsivity and dissociative experiences, rather than focusing only on formal diagnoses.

The study was conducted by Virgil Zeigler-Hill and colleagues, who analyzed three samples totaling 4,993 participants: 529 U.S. adults recruited through Prolific, 2,478 undergraduates at a large Midwestern U.S. university, and 1,986 Israeli adults recruited through advertisements and social media. Participants completed scales measuring perceived childhood harshness, such as chronic hardship or financial strain, and childhood unpredictability, such as unstable routines, caregiving and family circumstances, along with measures of four borderline trait domains.

Across all three samples, people who recalled more unpredictable childhoods reported higher neurotic, antagonistic, disinhibited and dissociative borderline traits. PsyPost reported that childhood harshness showed a less consistent pattern: its links with borderline traits often weakened or became nonsignificant after unpredictability was accounted for. In the two U.S. samples, unpredictability tended to have the strongest association among participants who reported lower harshness, while the pattern was less pronounced in the Israeli sample.

The findings matter because they point to childhood predictability as a potentially important developmental factor beyond exposure to adversity alone. However, the article notes key limits: the studies were correlational, relied on adults’ retrospective self-reports, used nonclinical samples and cannot show that unpredictable childhood environments caused later borderline traits.