Effect of Genes on Personality

Effect of Genes on PersonalityTo do what extent do genes sour mavens constitution?Personality is, traditionally, one of the just ab let out important objects of study for psychologists due to its study contribution to private disparitys. forward look into explored the mystery of human temper to whatsoever extent, passel bit by bit realize what determines their behaviours, why somebody feel excited in a certain situation time incompatibles do not. However, there is still wide debate with respect to various perspectives of character. First debate is about the exposition of temper which is much much complex than e veryday uses of this term. It can weigh on what psychologists believe about the causes and validation of reputation. A generally sure definition was proposed by Robins who defined personality as the distinctive and comparatively enduring ways of thinking, feeling and acting that characterizes a persons response to life situations (Robins et al, 2007). Further more, psychologists also ask what causes personality differences? Why some jibe raised in the self analogous(prenominal) family could claim different personalities while others could shit more similar personalities (Bouchard et al. 2001)? It is generally believed that personality is formed at a lower place the combing effect of genes and environment (Riemann et al., 1997 Bouchard et al.,2001 Caspi et al., 2002) however, there is no final shutting about to what extent genes and environment influence personality. Some psychologists suggest that genes could chance a more important role in shaping ones personality than environment (Schuett, 2013), and some believe that the plasticity of personality is lost after the age of thirty, that is, good deals personality mud constant as a result of their unchanged genes (Conley, 1985). In this essay, the influence of genes on personality will be discussed and evaluated in relation to both(prenominal) perspectives Eysencks biol ogical basis personality possibility and twin studies carried out by various psychologists (Eave et al., 1989 Bouchard, 1997 Waller, 1999 Jang et al., 1996).One important theory which is still regularly cited today is Eysencks biological basis personality theory (Eysenck 19xx, 19xx Eysenck and Eysenck, 19xx). This theory explains individual differences in personality in terms of genetic factors found on Eysencks abundant tether theory, which is one of the major(ip) theories and instrument for assessing personality traits. According to Eysencks direct, Peoples personality traits can be classified according to three dimensions Neutroticism the extent to which people live on negative emotion extroversion the extent to which people privilege to be alone or with others and Psychoticism the extent to which people be tough-minded. by and by the description of gigantic three theory, Eysenck states (1985) that there are both major systems responsible for physiological and psyc hological variations surrounded by individuals the reticulo-cortical which is placed in the judgement-stem reticular formation as well as the reticulo-limbic which is located in the visceral area and which consists of the amygdala, hippocampus, septum, cingulum and hypothalamus (Eysenck, 1985, cited in Matthews Gilliland, 1999). Although mutation can occur, these differences in the cortex are genetically determined. According to Eyseneck (1985), differences in the Reticulo-cortical could determine whether soul is extroverted or introverted, as the reticulo-cortical controls the cortical arousal produced by daring impulses which determines levels of motivation, emotion and condition depending on either inhibitions or excitations of the cerebral cortex. To illustrate, Eysenck claims that introverts are more likely to be cortically arouse than extraverts, as a consequence, they are likely to generate larger arousal by themselves than extraverts when they are in hardly the same s ituations such as in a party (EysenckEysenck, 1985, cited in Matthews Gilliland, 1999). Discrepancy between cortical arousal of extroverts and introverts, which arouse a genetic origin, means that the former feel comfortable to gurgle to people in the party because they are seeking external remark compensating for their low level of arousal, while the later remain quiet as they possess higher level of cortical arousal in their flair and do not need the external stimulation (ibis).Eysenck also accounts for peoples emotional stability in terms of reticulo-limbic activities (Eysenck Eysenck, 1985, cited in Matthews Gilliland, 1999). Reticulo-limbic in the brain controls peoples response to emotional stimuli. Emotional stimuli induces arousability of limbic system. Eysenck states that the brains of neurotic people are more easily aroused than emotionally stable people (ibid). The arousing activities can then be translated into a predisposition to experience intense emotions suc h as anxiety or sadness. Therefore, when the same event happens to neurotic and stable person, strong arousability could be generated by the brain of the former, as a result, he or she may response intensely either psychologically and physiologically, on the contrast, little arousability is generated in the brain of the later, conduct to very few response in return (ibid).A major restriction of Eysencks particular biological account of personality is refer with its testability. The difficulty to test Eysencks hypotheses is respectable, especially due to the lack of suspend technological instruments (MatthewsGilliland,1999). For example, a measure of cardiovascular activity is sometimes used to measure arousal differences between introverts and extraverts. However, the cardiovascular system has a considerable interaction with the respiratory system which could be a fuddle multivariate in this experiment (ibid). It is very difficult for scientists to exclude all confounding var iables and reach a valid result, hence it is difficult to verify the kinship between arousability of brain and personality traits. Nevertheless, nurture experiments carried out by other psychologists offer evidence that Eysencks biological theory was not as well substantiated as predicted. To illustrate, associations between extraversion and tonic measures of central ill at ease(p) system and automatic nervous system arousal are in truth much weaker than that were expected from Eysencks prediction (ibid.). It is worth considering, therefore, whether there is whatsoever other more important factor natural endowment rise to the differences between extraverts and introverts apart from arousability of cortex as proposed by Eysenck.While the genetic account of personality theory proposed by Eysenck (1985) has remained purely theoretical and is difficult to substantiate, more recent research on twin studies also reveals that personality could by and large be influenced by genetic fac tors (Eave et al., 1989 Bouchard, 1997 Waller, 1999 Jang et al., 1996). Twins can be split up into two types monozygotic (MZ) and dizygotic (DZ) twins. Monozygotic twins come from the same fertilized egg and are, therefore genetically akin. Dizygotic twins refer to twins who come from two separate fertilized eggs and only share half(prenominal)(a) of their genetics. In the study of influence of genetics and environments on personality, twin studies get up to be an important strand of research (Bouchard, 2001). Because MZ twins shared out exactly the same genes, it is reasonable to assume that any variation in their personality could be attributed to environmental differences in their upbringing, which indicates, to a certain extent, the possible environmental influence on personality. Meanwhile, DZ twins shared only half of identical genes and most of them are raised in the same environment. Their personality differences could more often than not be a result of genetic variat ions instead of environmental influence. In 1989, Eaves et al. carried out twin studies using the Gigantic Three(Eysenck, 1985) as three major personality dimensions and differences between twins personality traits( Neuroticism, Extraversion and Psychoticism) were indeed investigated. Twin meta-analysis suggested a nearly zero correlation between shared environments and twins personality traits for all three traits, while correlation for MZ was in two ways that for DZ, indicating that genes play an important role in this difference. Eaves et al. then used pitchman heritability to describe the heritability of a personality trait based on the difference between twin studies. The Falconer heritability for Extraversion, Neuroticism and Psychoticism was 0.58, 0.44 and 0.46 respectively, which means rough half of ones personality traits could be inherited from call forths (BouchardLoehlin, 2001).While Eysenck (1985) set forth personality traits according to his Gigant three and pro posed a genetic account for them. rib and McCare (1992) proposed an alternative personality trait theory the Big Five which classifies personality trait into Extroversion, Neuroticism, openness to experiences, agreeableness and conscientiousness.Neuroticism can be depict as the tendency to experience negative emotions, notably anxiety, depression and anger. Extraversion refers to high activity, the experience of positive emotions, impulsiveness, assertiveness and a tendency towards neighborly behavior. Openness to experience represents the tendency to engage in intellectual activities and experience new sensations and ideas. Agreeableness refers to friendly, considerate and modest behavior. Conscientiousness is associated with proactivity, responsibility and self-denial (Costa McCare, 1992, p.xx).There are psychologists, however, who suggested that the Big five model is a more robust and superior interpretation of personality traits compared to Gigantic three, as it could includ e wider personality scales in the input data(AzizJackson,2000) and more scientifically gratifying nowadays. Similar twin study of the Big five rather than the Gigantic Three was conducted. Those studies yielded similar results as those for the Giant three (Waller,1999 Jang et al., 1996a Riemann et al ., 1997), stating that around 40 per cent to 60 per cent personality traits was influenced by genes and the succour of them most influenced by non-shared environment(also 40-60 per cent).Although twin studies(Eave et al., 1989 Bouchard, 1997 Waller, 1999 Jang et al., 1996) has provided a relatively convincing effect for the question to what extent do genes influence ones personality, studies from different researchers have not always provided consistent results (BouchardLoehlin, 2001). Furthermore, a main limitation of all twin studies is that MZ twins can not be hardened as a homogenous group. MZ twins can be further divided into two types monochorionic MZ twins who share the sam e placenta and amniotic hammock and dichorionic MZ twins who do not. Sharing the same placenta means the twins have the same antenatal environment, which could lead to their higher correlation in personality traits. However, this high correlation was not resulted from similarity of genes but the same prenatal environment. This could be a large confounding variable of twin studies, giving rise to larger proportion of genetic accounts than reality. REFIn conclusion, both Eysencks biological basis of personality theory and twin studies have revealed that genetics can play an essential role in the formation of ones personality. However, limitations of these theories and experiments exist and cannot be excluded due to difficulties of current technology. On the other hand, it is worth pointing out that the extent of influence of genes and environment have on personality could be different depending on individuals. For example, people in adverse situations are more likely to change their personalities sharply, while those without massive change happened in their lives could keep relative constant personalities. Nevertheless, it is still very difficult to draw a valid conclusion more research needs to be conducted in this field in the future in order to draw a more valid conclusion.ReferencesChamorro-premuzic, T. (2011). Personality and individual differences (2nd ed.) 46-48. Blackwell Sussex.Eysenck,H.J.(1981) General features of the modal. In H.J. Eysenck(Ed). A model for personality. Berlin Springer-Verlag.Eaves, L.J., Eysenck, H.J., and Martin, N.G.(1989). Genes, culture and personality An confirmable Approach, Academic Press, New York.Eysenck, H. J., and Eysenck, M. W. (1985).Personality and individual differences, Plenum, New York.Matthews, G and Gilliland, K (1999). The personality theories of H.J. Eysenck and J.A. 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