Borderline Personality Disorder (BPD) is a frequent disorder with a pronounced suicidal risk. BPD is characterized by affective instability, intense interpersonal relationships, lack of stable sense of the self, and impulsive behaviour. Early relationships with caregivers frequently include verbal, emotional and physical abuse or neglect. This can set up an approach-avoidance conflict in child.

Attachment is a cognitive and emotional development theory in the context of interpersonal relationships. In BPD, attachment is either unresolved in relation to their parents; fearful or preoccupied in close relationships.

Genetic factors might be implied in some of the main characteristics of BPD: impulsivity and affective instability. Impulsivity might represent a heritable endophenotype link to serotonergic activity. Affective instability seems to be related to cholinergic and noradrenergic systems. These traits constitute a vulnerability to dysfunctions in infancy relationships.

Disorganized attachment in BPD can come from the encounter between genetic factors and a social environment witch is both threatening and comforting. Disorganized attachment can be considered as an adaptive strategy to protect against abuse and a disruption in affective communication without correcting. It could give rise to multiple, fragmented and incoherent Internal Working Models and to a deficit in mentalization. This could explain emotional instability, the mutable relational style, the identity disturbance and the self-damaging behaviours in BPD.

Finally, we propose that BPD should be considered as the result of interactions between attachment behavioural system and biological traits during the development of the child. Improved methods to measure fundamental genetic dimensions of BPD are needed.