Personality tests and their validity and reliability

INHERITANCE OF PERSONALITY
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Introduction
Biological inheritance is passing off traits from parental organism to offspring. Inheritance is governed by genes which determine an individual’s behaviour and traits. In human beings genetics and evolutionary theory are responsible for human being’s personal traits and behaviour. For instance, there is a correlation between addiction, skin color, disease disorders and genetics. Genetics and the progressive evolution that occurs in the environment are responsible for behaviors and personality. Personality is defined as individual difference among human beings in emotions, physical characteristics, behaviour patterns and emotions. Evolutionary theory and genetics are responsible for determining personality. Therefore, are certain behaviors and physical characteristics inheritable and common among certain races and ethnicities?
Literature Review
According to Buss (2009), evolutionary processes have not only the sculpted human body but also the brain, the behaviour and psychological mechanisms in human beings. The mechanisms are hypothesized as adaptations that contribute to personality, survival and inheritance of behaviour. The mechanisms are based on Darwin’s concept of sexual selection and natural selection. The concepts have great heuristic value in the behaviour and personality of human beings. In addition to that, Buss (2009), insists that evolutionary development psychology is useful in exploring important ontogenetic events that affect the development of sexual behaviour.

Evolutionary psychology is responsible for defining psychological disorders especially when human traits and behaviors fail to function the way they were designed to function. It also explains common affiliations such as sexual disorders, eating disorders, depression and anxiety disorders.
For Davidson (1999), evolutionary theories assist in explaining how evolution has shaped the behaviors, mind and personality of human beings. The human brain is made up of many functional mechanisms known as evolved cognitive mechanisms or physiological adaptations that are designed in the natural selection process. Examples include; sex-specific mating preferences, language acquisition modules, agent detection mechanism, alliance-tracking mechanism among others. For him, the mechanisms are directly linked to an individual’s traits and behaviors.
Bates & Wachs (2014), Suggests five theories of studying who we are and why we are similar or different to others. He explains why people have different characteristics. For instance, the difference in the color of the eye, hair and height. He insists that individual differences can be studied through developing descriptive taxonomies by comparing the ability and personality. Evolutionary psychology, behaviour genetic, biological theorizing, social cognitive and psychoanalytic theories are discussed by Plomin (2014), to address why people are similar yet are different in traits and behavior. The evolutionary psychology focuses on the universality of behaviors of individuals and tries to explain personal variability regarding optional adaptive strategies. Behaviour genetic approach analyzes personality variation regarding the composite interaction between genetic composition and the environment. Biological theorizing focuses on the continuity of personality and behaviour across human beings and explores biological foundations complex and temperament behaviour. On the other hand, social cognitive emphasizes the significance of socialization, and it impact in creating one’s unique personality and patterns of behaviour. The five theories prove that genetics has between 40-60% contributions of personality. All variations and heritability have their foundations on genetics.
However, Zuckerman (2011), insists that genes do not code for behaviour, feelings or emotions but instead code for proteins that modulate and regulate the function of the biological system that contributes to our behaviors. In this regard, brain structures and specific neurotransmitters can be linked to wide class approach to behaviors, personality and positive effects. Alleles are related to specific personality behaviour and traits that are influenced and moderated by experience in the environment. The sensitivity and personality of an individual are varied by subtle differences in availability and uptake of neurotransmitters. Through this way, behaviour sand cues are perceived, attended to, stored and incorporated with the previous life experiences to make an individual unique. The current work is understanding the delicate interaction between personality, behaviors and the environment.
Genetics and personality
As stated earlier, personality consists of the differences among human beings caused by physical characteristic or behaviour. Scientifically, genes do not influence behaviour but are responsible for certain behaviour in individuals. It is this behavior that make us different from other people and hence we possess different personality. Genes are responsible for personality traits such as addiction, different color of the eyes and certain disorders. However, the genes do not work in isolation and are heavily influenced by the environment.
The Genetic theory explains drug addiction and interpersonal relationships. The theory tries to separate environmental and genetic factors of addictive behaviour. For instance, children who are born and raised by alcoholic parents have 3-4 increases in alcoholism rate among the rest of the population. This indicates that there is a direct relationship between genetics and alcohol predisposition. What makes this a subject of discussion is how different human beings respond to alcohol. For instance, Asians, American-Indians and Eskimos are hypersensitive to alcohol. They instantly and extremely respond to alcohol in their blood system. They are genetically susceptible to a deficiency in the generation of acetaldehyde enzyme that is vital for degrading alcohol. In addition to that, the American-Indians and Eskimos become predisposed to other addictive behaviors such as gambling when they take alcohol. This is used to justify whether a single gene can be responsible for multiple behaviors (Azar, 2002). Therefore, alcohol addiction is inheritable and has similar effects on American-Indian, Eskimo and Asian races.
Another instance of correlation between genetics and personality is the variation in the eye color. Different races and ethnicities have different eye color that creates a difference. The eye color ranges from hazel to blue, brown and red among others. Sometimes, genetic mutations can cause a change in the melanocytes that are responsible for eye color leading to unusual eye colors such as violet (Arnold, 2011). During the recombination of the parent’s genes, some modifications can arise in the eye color genes of the parent. This is responsible for the different eye colors. Therefore, the color of the eye is determined by the interplay of genes and environment and is inheritable.
The red hair among certain ethnicities is a clear demonstration of the effect of genes on personality. The red hair is caused by recessive genetic trait as a result of mutations in melanocortin I receptor (gene) found in the chromosome 16. Since it is a recessive gene, the offspring has to inherit it from both parents. As a result, the number of the people carrying the gene are higher than those having the red hair. An example is Scotland where over 13% of the total populations have red hair. It’s for this reason that the ancient Greeks and Romans branded the Celts as redheads. Individuals with red hair are common in Western European countries of France, United Kingdom, Portugal, Spain, Germany, and Netherlands among others (Azar, 2002). Therefore, red hair is common in Western Europe and inheritable.
Are there genes for personality?
Definitely, the answer to this question is no. There is no specific gene for personality. However, genes are responsible for certain behaviors and characteristics. It is these characteristics and behaviors that make us possess different personality and individual behaviour. However, there are some personality dimensions that cuts across all races and cultures such as neuroticism and novelty seeking that can provide a foundation for determining the gene for personality. Certain scientists have insisted that genes account for only 1 to 2% of our traits. However, other scientists disagree with these as human beings have various unique personality, and hence it means that several genes are responsible for a single personality or behaviour (Gale & Eysenck, 2012). Scientists are now working to link the genes responsible for neuroticism and depression. For instance, Kenneth Kendler the Director of Psychiatric Genetics Research Program at Virginia Commonwealth University conducted a research that shows the link. He found out that depression and neuroticism share about 60% of their genes. The genes are responsible for certain personality traits and also plays crucial roles in psychopathology. The findings of Kenneth Kendler proves that conditions such as anxiety disorders, depression and deficit in attention are connected by common genes. Therefore, certain genes are responsible for our personal traits.
Conclusion
Genes are responsible for our personal traits. There are common genes among individuals of the same race, ethnicity or culture. Such common genes are responsible for certain behaviors and characteristics that create different personality among individuals. For instance, Eskimos, Asians and American-India possess genes that limit the generation of acetaldehyde enzyme resulting in certain common behaviour. The same applies to the common red hair among Celts and Western Europe. This proves that certain traits, characteristic or behaviour are common among certain races or ethnicities and are inheritable.
References
Bates, JE. & Wachs, TD. (Eds.). (2014). Temperament: Individual Differences at the Interface
of Biology and Behavior. American Psychological Association
Beth Azar, (2002). Searching for Genes that Explain our Personalities. Vol, 33 No. 8. Retrieved
from http://www.apa.org/monitor/sep02/genes.aspx on December 12, 2015.
Buss, D. M. (2009). The great struggles of life: Darwin and the emergence of evolutionary
psychology. American Psychologist, 64, 140-148
Davidson, R.J. (1999) Biological Bases of Personality. In Derlega, V., Winstead, B.A., Jones,
W.H. Personality: Contemporary Theory and Research. (2nd Edition). Nelson Hall, 1999, Chicago.
Gale, A., & Eysenck, MW. (Eds.). (2012). Handbook of Individual Differences: Biological
Perspectives. Chichester: Wiley.
Paul Arnold, (2011). What Determines Eye Color? Retrieved from
http://www.brighthub.com/science/genetics/articles/38797.aspx on December 12, 2015.
Plomin, R. (2014). Genetics and Experience: The Interplay between Nature and Nuture.
Thousand Oaks: Sage.
Zuckerman, M. (2011). Psychobiology of Personality. Cambridge: Cambridge University Press.