Due to the higher diagnostic prevalence of borderline personality disorder (BPD) in females, there exists a dearth of literature on the manifestations of BPD in men and minimal information on male developmental trajectories to the disorder. To identify precursors of BPD in males, surveys were administered to parents about their BPD male offspring and non-BPD male siblings. Questions covered aspects of probands' lives from infancy to late adolescence. BPD offspring were identified through self-reported clinical diagnoses and standardized diagnostic criteria embedded within the survey. A total of 263 male offspring (97 meeting strict criteria for BPD and 166 non-BPD siblings) were studied. The authors found that parents describe the early emergence of a constellation of symptoms in their BPD sons that include separation anxiety starting in infancy, body image concerns in childhood, and impulsivity, emptiness, and odd thinking in adolescence. This trajectory differs from the developmental course found in females diagnosed with BPD.