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Reflection: Biological and Environmental influences on Personality
The traditional view about personality development has been that environmental and
genetic factors both play a role in the personality development of humans. However, a greater
understanding of the brain functioning has led to the observation that genetics and brain
physiology have a greater impact on personality that was previously thought. The increase in the
prominence of genetic and brain anatomical structures in explaining personality does not mean
that environmental factors do not play an important role in shaping personality.
The relationship between traumatic brain injury and personality change has provided
some of the strongest evidence that anatomical changes, rather than environmental factors, have
the greatest effect on personality. Fowler and McCabe (2011) reveal that following traumatic
brain injuries, about two-thirds of individuals experience changes in their cognitive, behavioral,
and emotional functioning. While it is true that the anatomical changes in the brain can
contribute to personality changes, environmental factors can be used to control these changes.
Fowler and McCabe (2011) reveal that the injured individual can engage in social skills training
to inhibit inappropriate behavior and improve retrieval of rules of social interaction. The use of
social training to adjust behavior is in line with the view that while personality is biologically
based, learning experiences can reshape the developing brain (McCrae, et al., 2000).
Genetics are not always able to explain the behaviors of individuals. Siblings who have
genetic relatedness can exhibit markedly different temperance and personalities. Turkheimer and
Waldron (2000) declare that siblings from the same family tend to be no more similar compared
to children chosen at random from the population after factoring in genetic relatedness. This
suggests that an understanding of genetics and brain physiology cannot fully explain the
personality development of humans. The environmental factors can help shed light onto the
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personality outcomes of the siblings. According to Turkheimer and Waldron (2000), the
environmental differences experienced by siblings explain the variance in their behavioral
outcomes.
The argument that genetics influence behavior is strengthened when reviewing behavioral
disorders. Studies demonstrate that genetic factors can best explain personality disorders
witnessed in siblings. South (2015) documented that there are shared familial risks for certain
personality disorders with one twin study showing that prevalence of major depression,
borderline, avoidant, and paranoid personality disorders could be attributed to one genetic factor
shared by the affected twins. However, while genetics predispose the individuals to inherited
personality disorders, the environment within which the person is raised determines whether they
will develop some of the disorders. South (2015) acknowledges that the development of avoidant
personality disorder is largely determined by the environment within which the individual is
raised. This view is supported by Rutter and Silberg (2002) who observe that gene-environment
interactions influence personality. This shows that a comprehensive understanding of personality
must consider environmental factors.
The increase in knowledge about the brain and the functions of its various components
have led to a better understanding of the impact of brain structure on personality. Findings in the
field of behavior genetics have also demonstrated the role genes play in determining individual
personality. This paper has shown that these revelations do not render environmental factors
irrelevant. The biological and environmental factors often act together to influence personality. It
can therefore be declared that studying the great psychological theorists such as, Freud, Skinner
and Maslow will remain crucial to developing a better understanding of personality
development.
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References
Fowler, M., & McCabe, P.C. (2011). Traumatic brain injury and personality change. Pediatric
School Psychology, 39(7), 4-10.
McCrae, R. Et al. (2000). Nature over nurture: Temperament, personality, and life span
development. Journal of Personality and Social Psychology, 78(1), 173-186.
Rutter, M., & Silberg, J. (2002). Gene-environment interplay in relation to emotional and
behavioral disturbance. Annual Review of Psychology, 53(1), 463-491.
South, S.C. (2015). Biological bases of personality disorders. In S. K. Huprich (Ed.), Personality
Disorders: Toward Theoretical and Empirical Integration in Diagnosis and Assessment
(pp. 163-201). American Psychological Association.
Turkheimer, E., & Waldron, M. (2000). Nonshared environment: A theoretical, methodological,
and quantitative review. Psychological Bulletin, 126(I), 78-108