Family may be viewed as a system of relationships in time context. Neurobiological research findings increasingly provide data about the way relationships are reflected in one's brain. A common conclusion is that how one perceives his/her place in a relationship may modulate the activity of neurotransmitters, and their cerebral functional consequences.

The data come from laboratory animals from primates to laboratory mice. These include baby monkeys' reaction to separation with increased cortisol and ACTH, apparently associated with a genetic vulnerability. The neurobiological alteration, however, may be reversed by overnurturant mothers, and these changes are parallelled by behavioral changes.

Mice lacking a version of a protein that recognizes estrogen, called estrogen receptor beta or ER-beta, are inept at recognizing familiar animals and may have abnormal molecular responses to social stress. Those may become future anxious mothers who also show diminished capacity for normal social interaction and are socially subordinate. A similar observation applies to trauma-related changes that do not manifest themselves until late adolescence, due to increasingly limited cortical modulation of limbic, brainstem and midbrain responses to fear and danger. Gene-environment interactions are responsible not only for the disorders, but also “normal” states of mind, leading to a wide variation of relational and behavioral changes within the normal population. Simple perturbations of metabolism may trigger differential responses as shown in a recent study of folate and homocystein levels.

Based on these findings, it is conceivable to speculate about the possibility that the patients' habits of relatedness and the way they are encoded in the infant brain (in the form of memory and its compartments) may be shaped by family-based therapies via alterations in the way genes express themselves and how these changes may become permanent.