A common misconception is that genetics alone can predict whether one will develop a disorder. This misconception has led to fear about a future where one’s genes could be used to discriminate them. This fear is reflected in the 1997 movie called Gattaca where the protagonist is deemed to have “inferior” genes and thus cannot pursue his dreams of space travel. Thankfully, the reality is different.

Genes alone cannot explain complex outcomes such as if one will be successful in life or if one will develop psychiatric disorders. To do so, require more than the genes, it requires also considering the environment in which an individual lives in. Furthermore, one needs to consider the complex interaction between genetics and the environment in order to really understand and predict such a complex etiology.

When there is a gene-by-environment interaction (GxE) (which we observe in psychiatric disorders), we have that certain genes moderates the effect of the environment on future outcome. In other words, with certain genetic variants, one will be less susceptible to the environment, while with certain other genetic variants, one will be more susceptible to the environment. We generally observe three types of GxE patterns: 1) diathesis-stress, 2) differential susceptibility, or 3) vantage sensitivity.

Diathesis-stress stipulates that some individuals carry “risk” genes that make them disproportionately susceptible to adverse environmental conditions (Zubin & Spring, 1977); (b) vantage sensitivity stipulates that some individuals disproportionately benefit from supportive conditions due to their genetic make-up (Pluess & Belsky, 2013); and (c) differential susceptibility stipulates that some individuals are more developmentally plastic “for better and for worse” (Belsky, Bakermans-Kranenburg & van IJzendoorn, 2007), thus, they are more susceptible to both negative effects of adversity and beneficial effects of support (Belsky, 1997a, 1997b).

References

1. Bakermans-Kranenburg, M. J., & van IJzendoorn, M. H. (2015). The hidden efficacy of interventions: Gene× environment experiments from a differential susceptibility perspective. Annual review of psychology, 66, 381-409.
2. Belsky, J. (1997a). Theory testing, effect‐size evaluation, and differential susceptibility to rearing influence: The case of mothering and attachment. Child development, 68(4), 598-600.
3. Belsky, J. (1997b). Variation in susceptibility to environmental influence: An evolutionary argument. Psychological inquiry, 8(3), 182-186.
4. Jolicoeur-Martineau, A., Belsky, J., Szekely, E., Widaman, K., Pluess, M., Greenwood, C., & Wazana, A. (n.d.). Distinguishing differential susceptibility, diathesis-stress, and vantage sensitivity: Beyond the single gene and environment model. Development and Psychopathology, 1-11. doi:10.1017/S0954579418001438
5. Pluess, M., & Belsky, J. (2013). Vantage sensitivity: Individual differences in response to positive experiences. Psychological bulletin, 139(4), 901.
6. Zubin, J., & Spring, B. (1977). Vulnerability: A new view of schizophrenia. Journal of abnormal psychology, 86(2), 103.