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Persistent exposure to family aggression – between parents or directed at the child(ren) – has been found to modify the biological reactions that children have when confronted with conflict. These effects can be seen all the way through to adulthood. This may explain why people who have experienced aggression in childhood are more likely to show (but by no means necessarily so) more aggression in adult relationships.
Gayla Margolin and her colleagues at the University of Southern California looked at many different pieces of research to work out the connection between early experiences of aggression and more aggression in later adult relationships.
Biological reactions to persistent stress
A normal response to a threatening situation features a short-term increase in heartbeat, attention and mobilisation of energy – popularly known as the “fight or flight” response – followed by a decrease in all of these when the danger has passed. The level of the stress hormone cortisol rises and falls during this process.
But if a threat is constantly encountered, stress responses may not turn on and turn off normally – individuals may experience persistently high reactive states, or persistently low ones. Children exposed to repeated stress develop this lack of ability to regulate reactions. Conversely, sensitive care helps children react less physically and is associated with resilience to stress in later life.
Influence of childhood experience of aggression on biological response to conflict
Various pieces of research have looked at how children, adolescents and adults with experience of family aggression in childhood react biologically in conflicts with others, compared with children with no childhood history of family aggression.
Exposure to family aggression when young can produce heightened biological reactions or suppressed reactions in conflicts later in life. The research suggests that the reaction tends to be heightened in novel situations – with a friend or a partner – and dampened in repeating situations, for example, teenager-parent conflicts.
Babies and children
In one experiment, the cortisol responses of 7-month-olds from homes with punitive parenting or aggression between parents rose more when they were presented with emotionally challenging tasks.
In another research project, children exposed to higher marital conflict who also reported high levels of self-blame and fear of threat showed a greater increase in heartbeat.
Another piece of research reported that girls with chaotic or coercive father-daughter relationships had higher cortisol levels when discussing problems with a friend.
In one experiment, cortisol levels were measured in adolescents when talking about topics that produced conflict between parents and children. Adolescents who had experienced repeated family aggression showed less increase in cortisol, and this appeared to protect against a strong reaction; perhaps they were filtering out the adverse stimuli.
In one experiment, a simulated conflict with a neighbour triggered less cortisol in young adults who had experience a lot of family conflict.
In a study of maternal sensitivity during childhood, less sensitive caring was linked with more sweating during arguments with partners. In another study, wives who reported aggression in their families of origin showed higher cortisol activity during arguments with their husbands.
How biological reactions in relationship conflict influence behaviour
Research shows that when there are higher biological responses to relationship conflict, there is more likely to be aggression. However, the relationship is complicated because many other individual circumstances other than history of family aggression—such as depression or participation in risky or antisocial behaviour—can influence behaviour.
What happens when two individuals with different family histories form a relationship? They can influence each other. In the study mentioned above of a wife’s higher cortisol activity during an argument, the husband’s cortisol level was also higher. And if a person who has a history of family aggression partners with someone who does not have such a history and is nurturing, do biological responses change over time? Indeed, to what extent can later relationship experiences generally modify a childhood experience of family aggression?
Margolin G, Ramos MC, Timmons AC, Miller KF & Han SC (2016), Intergenerational transmission of aggression: Physiological regulatory processes, Child Development Perspectives, 10.1