Generational Trauma: A Genetic Component


By Michelle Mukonyora

1 October 2017

Zimbabweans have experienced complex trauma. Trauma that is repetitive and cumulative: from the First and Second Chimurenga wars, to Gukurahundi, to Murambatsvina, and 2008. Today, we continue to face violence (sexual, political), and economic pressures that feel burdensome. Annie Murphy has a brilliant Ted Talk titled ‘What We Learn Before We Are Born’. It was this talk that made me want to explore the prenatal factors that contribute to depression, and to start thinking of trauma as being “contagious”. Trauma is devastating not only for the person who has suffered it, but for future generations.

Murphy highlights a study conducted following the September 11 attacks, which revealed that pregnant women who experienced post-traumatic stress disorder (PTSD), gave birth to babies with susceptibility to PTSD. Comparable cases have been observed amongst children of war veterans. Many of us have heard snippets of the traumatic experiences our parents and grandparents experienced during the liberation struggles, both directly and indirectly. There is the obvious effect of trauma being passed on by personal interactions. But stress also leaves genetic imprints, known as epigenetic changes. Epigenetic changes are chemical changes to the DNA, which do not change the message encoded by the DNA but affect the way in which the message is conveyed: Louder, softer, silent.

Early life stress causes inheritable depressive behaviour
An interesting study showed that young male mice exposed to stressful situations, and with no comfort from their mothers grew up having depressive behaviours. They also tended to underestimate risk in adulthood. The children and grandchildren of these male mice showed similar depressive behaviours. To eliminate the social aspect of passing on trauma, the genetic material of the first generation of male mice was used to fertilise eggs from non-traumatized mice, and the depressive behaviours were still inherited. The exact mechanisms through which this happens are not yet clear.
A mother’s diet affects the baby’s metabolism
Murphy also discusses research, which suggests that the mother’s diet while pregnant affects the way in which a baby metabolizes food. Basically, the diet in the womb helps shape and prepares the foetus for life outside the womb. Mothers that eat abundantly birth babies with metabolisms designed to metabolise food consumed in abundance. In some cases, pregnant women with restricted diets will birth babies that are exposed to an abundant diet. These babies ultimately become susceptible to chronic diseases such as obesity, high blood pressure, and diabetes later on in life. Often, a lot of pressure is placed on women to adjust their lifestyles when trying to become pregnant. But it is now becoming clear that men also need to be mindful of their lifestyle choices. Sperm are equally susceptible to epigenetic changes. Alcoholism in men, for example, affects their offspring.
Nurturing plays a role in stress levels later in life
As early as 1997, a groundbreaking study illustrated that baby rats, which were licked and cared for more by their mothers, grew up expressing lower levels of stress hormones. Later on, it was found that baby rats nursed by inattentive mothers also grew up to be inattentive mothers. Epigenetic changes resulting in lower levels of the hormone oestrogen were implicated in this phenomenon. Studies of this nature have now evolved to human studies. Work like this is important, as it highlights the importance of dealing with conditions such as post-natal depression. The repercussions of poor mother-child bonding may have generational impacts.
Suicide. A genetic element
Suicide is complicated. There are lot of misconceptions about why people feel suicidal, many of which are harmful. The brains of people who died by suicide have “excessive” epigenetic changes in the hippocampus region of their brains. The hippocampus plays an important role in memory and stress responses. For example, those who were abused as children, and committed suicide had these changes in their brains. Socioeconomic status of the family in early childhood also has a significant impact on the brain, and future emotional tendencies. Distinctly different epigenetic patterns are seen between men who had been either very poor or very rich as young children.
We clearly need to start tackling trauma at a genetic level. We need to incorporate genetics in how we deal with and treat downstream depressive disorders, long after the event has passed. In the African context, we also need to focus on how we can incorporate the spiritual and cultural dimensions into how we deal with trauma as a people. A story for another day.