When one hears the term depression, what often comes to mind is the image of an adult, overcome with a despondence so intense that they cannot get out of bed. Research in developmental psychology, however, has demonstrated that depression isn’t only rooted in childhood and adolescence but is also dictated by genes. Further, it’s a known fact that the COVID-19 pandemic has witnessed an increase in mental health problems such as anxiety and depression, as highlighted by the WHO. Given that poor mental health is associated with a variety of multidimensional consequences, it’s time to review risk factors in early life that can contribute to depression in adulthood, and identify means to control these effects. 

The concept of nature versus nurture has been discussed in the context of mental illness for a very long time. Emerging evidence has shed light on the impact of Adverse Childhood Experiences (ACES) on the development of depression in adulthood. Numerous studies have identified adverse childhood experiences such as abuse and household dysfunction as risk factors in the development of depression in later life. These findings shed light on the importance of controlling these risk factors from an early age, as their harmful effects spill into adulthood, in the form of worse mental health and depression. This effect has been demonstrated by Dangingo et al (2020), who found that among 162 depressed participants, ACEs were the most prominent predictors of depressive symptomatology, along with levels of education and physical illness.

Taking into account the age-old gene/environment debate, a growing body of literature has shed light on the genetic risk of developing mental health problems in adulthood. Studies have found a 37% heritability of depression through methods such as twin studies, and genome-wide association studies (GWAS) leading to groundbreaking research and new findings. For example, Akingbuwa et al. (2020), through a meta-analysis, found that the polygenic risk scores (estimation of effects of genes on the person’s physical state) of major depression in adulthood were positively associated with psychopathology in childhood. In addition to this, new findings have shown that having a family member such as a parent or a sibling with major depression increases an individual’s risk of developing depression by 2-3 times. These findings fall under the “nature” category of the debate, and findings in this field are only continuing to grow. Another perspective on depression involves an understanding that mental illness occurs along a pseudo-continuum. Professor Robert Plomin in his book Blueprint discusses mental illnesses occurring as part of the normal distribution, i.e., as extremes of the same gene occurring across the distribution (Plomin, 2018, p. 58, p. 60). In the book, he also describes the importance of DNA and aptly explains how “abnormal is normal”.

All these perspectives fall under the genetic versus environmental influence debate, and these arguments are nowhere close to concluding. However, all these findings and pieces of literature point to the fact that there is a complex play of both nature and nurture when it comes to mental illness such as depression. What these findings can do is help us understand what the risk factors are, which can in turn, lead to follow up research on protective factors, such as resilience. Modifying environmental aspects such as exposure to childhood maltreatment and ACES can help control the development of depression in adulthood. Newer methods in behaviour genetics will allow researchers to further study the genetics of depression, just like the way in which GWAS has changed the face of the field in recent years. At the end of it all, psychological research on mental illness will help reduce the stigma surrounding depression as something abnormal and help change policy on mental health.