Personality tests

By Megan Fawaz


Personality is the core of an individual. It is like the engine of a car, empowering individuals to reach their destination. It is useful to know how to troubleshoot a car engine when people find themselves stuck in the middle of the desert. An individual who understands their personality is the same thing. Knowing how their mind works, the person will appreciate themselves more and even respect how others manage to keep their engines running smoothly.


Physicians in Greece fought over the idea of personality from a date as early as the 5th century B-C (Gardiner, 1918). The term “personality” was first coined in the 18th century to describe the thinking, understanding, and behaviors people exhibit across various situations (Crocq, 2013). The concept gained stronger momentum when it became accessible to the public through the means of personality tests (Butcher, 2009). A personality test is a tool used to measure the characteristic patterns of traits in humans.

Types of Personality tests

Since the first psychological test, created by Dr Robert Woodworth in 1917 in the United States, there have been over two thousand tests put on the market (Lucy, 2012). Some of the most popular are the Big 5, Neo Pi-R, MMPI/MMPI-2, 16 PF, Eysenck Personality questionnaire, and the Myers-Briggs Type Indicator (MBTI), which is the most popular personality test in the world (Menand, 2018). This test was invented by Katherine Briggs and Isabel Myers and became the basis of a  two billion dollar industry (Block, 2018). Its popularity could partly be because it focuses on personality traits rather than temporary emotional states, like the Big 5 test. However, the MBTI is criticised for being unprofessional since it was created at home (Menand, 2018), The MBTI was very popular until the Education Testing Services (ETS), an organisation focused on educational research and assessment development (Arthur, 2018),  dropped the MBTI because they did not consider it scientific. There is still a lot of debate around the extent to which these personality tests are reliable and whether the ETS made the right decision in discontinuing the use of the MBTI.

Link between personality and gene expression

Animals need to be socially active to survive and reproduce. For instance, they find mates, hunt for food, defend and care for their offspring. The term “social” is used to describe behaviors that occur in a group of members of the same species that would not be present in isolated animals for example,communication (Floreano et al., 2007). Studies show that social activities can have global effects on gene expression in the brain (Mello et al., 1992) and trigger lasting epigenetic modifications of the genome (Champagne et al., 2003; Robinson et al., 2008). In addition, a study showed that certain personality traits such as conscientiousness and extraversion were linked to reduced and increased levels of pro-inflammatory gene expression, respectively (Vedhara et al., 2015). However, biological mechanisms underlying the relationship remain poorly understood. Epigenetic studies of these pro-inflammatory genes could provide a more in-depth understanding of this link.

Understanding the relationship between social behavior and genes has become easier due to  experimental genetics (Ren. et al., 2020). The genetic tools allowed researchers to determine genes linked to the social interaction of animal species with vibrant social lives, such as songbirds. For example, expression of egr1 can be induced with the sound of another songbird singing. Following the results of the NEO-FFI test conducted on humans, individual differences in the five personality traits were linked to the quantitative expression of two previously defined components of the CTRA gene expression profile (Fredrickson, 2013). These were upregulated expression of pro-inflammatory genes, and down-regulated expression of genes mediating Type I interferon antiviral responses and antibody synthesis (Robinson, 2015). A related study suggested that the association of leukocyte CRTA genes and personality traits could be largely predicted by the immune response system, i.e. stable personality traits arise in response to differences in biological vulnerability to infection. (Napolini, 2014). For example, low levels of pro-inflammatory gene expression would be interpreted as a weak immune system that requires fairly cautious behavioral tendencies including introverted behavior (to avoid socially transmitted infections) and conscientious behavior (to reduce vulnerability to risky behavior) (Napolini, 2014). Further research would help to determine whether and how personality traits are associated with the genetic make-up.

A benefit of such studies would be to discover other genes responsible for long-term personality traits. Then, knowing one’s personality, for example, by taking a personality test, would allow an individual to speculate about their genetic makeup and relative gene expression levels.Based on this, they would be more aware of how social stimuli might affect them, and could make adjustments to, for example, help them overcome periods of low mood.


A personality test can be a great way for individuals to understand and appreciate themselves and others more. Being aware of how you think and perceive the world can greatly impact your social and professional life. Modern genetic technologies allow scientists to study personality at a molecular level.


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