Environmental Factors Related to the Development of Personality Disorders (Nurture)
As mentioned in the prior section, babies' temperaments are generally assumed to be genetically determined; but, babies' biologically determined temperaments are just a starting point. Clearly, babies do not grow up independently. Instead, babies are quite dependent upon their caregivers for their very survival and so these frequent interactions with parents or other caregivers have special significance. It is the emotional tone of these social interactions with caregivers, shaped by the "fit" between babies' temperaments and parents' personalities, which further influences the development of babies' personalities. This interaction between baby and caregiver provides a good example of how natural and nurturant forces interact with one another to influence personality development, so let's examine this bi-directional interaction a little more closely.
Infants demonstrate different temperaments from the moment they are born. Some infants are highly sensitive. They react swiftly and sharply to environmental stimuli, such as a bright light in their eyes, or a loud noise. Other infants react to these same stimuli more slowly, and without much interest. It is these sorts of differences that enable researchers to conclude that babies are born with different, genetically-determined, temperaments. Furthermore, their unique temperaments will influence how their environment responds to them. You can imagine that the highly sensitive, reactant babies will elicit a different response from their environment (parents and other caregivers) than will less reactant, more even-tempered babies. For example, a calm and placid baby is more likely to get picked up and cuddled more affectionately than an anxious and irritable baby. Of course, these different environmental responses will, in turn, affect the emotional development of each child. Many child development specialists agree that healthy personality development has a lot to do with the match between infants' temperaments and their caregivers' dispositions; and, if we generalize this process more broadly, a lot to do with the match between children's dispositions and their environment. Well-matched sets of infants and caregivers, are characterized by an abundance of positively-toned interactions with pleasant emotional exchanges between caregiver and child, and are thought to produce fewer negative personality outcomes than are poorly-matched sets, characterized by an abundance of negatively-toned interactions with unpleasant emotional exchanges.
A large body of research and clinical observation additionally supports the idea that childhood experiences play an important role in the development of personality traits and personality disorders. Traumatic childhood experiences such as physical, sexual, or emotional abuse and neglect, have been identified as risk factors which increase the likelihood that a personality disorder may develop (Johnson, Bromley, & McGeoch, 2005). Other adverse experiences in childhood, such as the death of a parent, the separation or divorce of parents, the lack of parental affection, poor family communication, a harsh and controlling parenting style, or exposure to assaultive bullying, may also heighten people's risk for developing features of a personality disorder.
The relationship between adverse childhood experiences and personality disorders is complex. While exposure to these events does heighten the likelihood that a personality disorder will occur later in life, it is not the case that all abused, or otherwise stressed children go on to develop personality disorders. This observation suggests that multiple risk factors (both genetic and environmental) must occur in some specific combination so as to overwhelm a child's system and cause them to later develop a personality disorder. It also suggests that various protective factors may exist that function to limit the negative effects of significant trauma and adversity. Access to social support and social involvement are the primary factors that appear to serve this protective function (Johnson, Bromley, & McGeoch, 2005). Generally speaking, abused or otherwise stressed children tend to have better outcomes when they have access to nurturing and supportive relationships with secondary caregivers who demonstrate the affection, warmth, and empathy that is lacking in their home (e.g., grandparents, neighbors, teachers, coaches, clergy, etc.).