What Shapes Who We Are and How We Live?

| June 26, 2012

Both genetic and environmental factors influence our development across multiple dimensions including physical, cognitive, affective, and social domains.  Genes are hereditary units that transfer heritable characteristics from one generation to another.  However, the mere presence of a gene doesn’t mean that a certain trait will definitely occur. In other words, genes need to be expressed in order to exert their effects.

As segments of the DNA molecule, genes are transcribed into corresponding m-RNA molecules and then translated into protein molecules (gene expression).  These proteins can be enzymes, hormones, structural components of the body, or elements playing other roles.  Moreover, DNA can replicate and give rise to cell proliferation. Together, protein synthesis and cell proliferation  contribute to  production of  certain biopsychosocial characteristics. However, genotype or biological tendencies do not produce a full human being independently; rather, they are influenced by a second key factor, the environment.  Environmental factors can turn genes on or off and thus exert a major influence on the consequences.  For example, methylation of the DNA molecule by some environmental factors may silence some genes and prevent their functioning (epigenetic influence). It is proposed that an individual who has genetic vulnerability to type 1 diabetes mellitus may develop the disease when some environmental influences such as viruses intervene and finally lead to autoimmune destruction of  pancreatic beta cells and disrupt insulin production. Similarly, an individual with  genetic vulnerability to schizophrenia or depression, may develop the respective disorder after going through life adversities or stressful situations (diathesis-stress model).
Genes  do not directly cause the production of  any specific feature, rather they set biological limits or upper and lower boundaries for a certain characteristic (reaction range). Then the environmental factors act to yield a certain characteristic within that range. For example, a certain genotype might lead to an IQ of 60 if the person is reared under maximally impoverished circumstances, or may yield an IQ of 160 under maximally nourished conditions.
To sum up, our personality and physical, affective, cognitive, and social features are shaped by the interaction between the genes and environment.  Therefore, we can help heal psychopathologies and  maladaptive patterns through providing nurturing environmental experiences.

References

1-Gottlieb, G. (1991). Experiential canalization of behavioral development: Theory. Developmental Psychology, 2 7, 4-13.

2-Champagne FA, Mashoodh R. (2009). Genes in context: Gene–environment interplay and the origins of individual differences in behavior. Current Directions in Psychological Science, 18, 127– 131.

3- Fowles, D. C. (1992). Schizophrenia: Diathesis-stress revisited. Annual Review of Psychology, 43, 303-336.