BackgroundBorderline personality disorder (BPD) is associated with high levels of stressful life experiences (SLEs). It is unclear if persons experiencing SLEs have more BPD symptoms after accounting for familial risk factors. Aims: One, create a predictive model of BPD using stressors across age and contexts. Two, examine if SLEs result in higher levels of BPD symptoms beyond genetic and environmental risk. MethodsThe sample comprised 2801 twins from the Norwegian Institute of Public Health Twin Panel. Poisson regression was used to explore which SLEs predicted BPD symptoms. Elastic net penalized regression was conducted to develop a predictive model for SLEs and BPD symptoms. Co-twin control analyses were performed to differentiate between environmental and genetic factors. ResultsSLEs in childhood and adulthood were associated with BPD symptoms. A weighted poly-event risk score explained 22% of the total variation in symptoms. Shared environmental and heritable factors explained 31% and 47% of individual differences in BPD symptomatology. Measured SLEs explained 42% of shared environmental risk for BPD. The predictive risk for BPD by SLEs was reduced when accounting for shared environmental and genetic factors. However, SLEs increased risk of BPD symptoms beyond shared genetic and environmental factors. ConclusionsBPD symptomatology following SLEs cannot fully be explained by genetic and shared environmental factors. The SLE-BPD symptoms associations were primarily due to selection by family environments. It is of importance to identify familial factors leading to both SLEs and BPD symptoms. SLEs remain associated with BPD symptoms when accounting for genetic and environmental confounding.