Borderline Personality Disorder (BPD) is a complex mental disorder characterized by instability in emotions, interpersonal relationships, self-image, and behavior. The causes of BPD are multifactorial, involving an interaction of biological, psychological, and environmental factors. No single factor alone is responsible for the disorder; instead, it develops through the combined influence of genetic vulnerability and adverse life experiences. Genetic factors play an important role in the development of BPD. Family and twin studies indicate that individuals with a first-degree relative suffering from BPD are at a significantly higher risk of developing the disorder. Heritability estimates suggest that genetic influences account for approximately 40–60% of the risk. Although no single gene has been identified as responsible, multiple genes related to emotional regulation, impulsivity, and stress response are believed to contribute. Genetic predisposition interacts with environmental experiences to increase susceptibility. Neurobiological abnormalities are another major cause. Brain imaging studies have identified structural and functional differences in regions involved in emotional regulation and impulse control. The amygdala, which processes fear and emotional responses, often shows increased activity, leading to heightened emotional sensitivity. The prefrontal cortex, responsible for decision-making and impulse regulation, may show reduced activity, making it difficult for individuals to control emotions and behavior. Alterations in the hippocampus, associated with memory and stress regulation, have also been observed. Neurotransmitter imbalances involving serotonin, dopamine, and norepinephrine contribute to impulsivity, aggression, mood instability, and emotional dysregulation. Psychological factors significantly