In discussing the mechanisms of how childhood personality traits can influence adult future developments, Hampson found that some personality traits of young ages have enduring effects on adults’ later life (Hampson, 2008). For example, adults who were not in control of self, temper, and orderliness in childhood are less likely to achieve academic success, stay employed, stay married and even stay out of life-threatening behaviors (Hampson, 2008). Specifically, there are three layers of psychological individuality over the life-course: 1. Dispositional traits; 2.Characteristic adaptations; and 3.Integrative life narratives (McAdams & Olson, 2010) with layer 1 at the core and layer 3 at the outer-most. This post will briefly discuss the early evolvement of temperament into the dispositional traits seen in adulthood, with a focus on the relationships between genes and environments.
Research (Muris & Ollendick, 2005) has found that young children (2 to 3 years old) who are impulsive and negativistic tend to show high levels of neuroticism, and low levels of agree-ableness and conscientiousness as young adults. Also, young children who are socially reticent grow up to be adults with higher levels of constraint and lower levels of extraversion. Numerous of other researches also show links between temperament and etiology of child psychopathology (Muris & Ollendick, 2005). Not only the discussion between genes and the environments further our understanding of the temperament-child psychopathology links, but it also contributes to the discussions of "Determinism versus Free choice" and "Biological versus Social influences".
Firstly, it was found to be very difficult to associate any single candidate gene with dispositional trait(s) (Munafò et al., 2003). In other words, a dispositional trait appears to be the product of multi-level, complex relationships among different genes within different environments. For example, children temperament can be formed as early as age 2 and while genetics may play a big role at that time, it is also the role of the parents who can either promote or suppress their infant’s temperaments in many different ways. Other caregivers also contribute to that complex gene-environment mix. Initial complexities lead to by-product complexities such as challenges with collecting accurate research data from different types of caregivers. Researches on identical twins also shown that no pair of identical twins grows up to be exactly the same (Feist, Feist, & Roberts, n.d.).
Secondly, it is possible to identify the link between a particular gene polymorphism and a human behavioral tendency within the context of other gene-environment mix. Capsi et al. showed that the promoter region of the serotonin transporter (5-HTT) gene may be influenced by major stressful life events (Caspi et al.,2003). For example, people who experienced at least four major stressful life events may have shorter allele of 5-HTT gene, leading to less efficient re-uptake of serotonin, consequently leading to higher levels of depression and suicidality. Furthermore, genetic differences may lead to different decisions on what kind of environments people want to be in. For example, in transitioning to adolescence and with the arrival of puberty,biological-driven agents such as hormones may cause both psychological and physical shifts, influencing self-esteem, individual differences, cognitive developments and so on. Emerging young adults then have stronger motivations to seek the kind of environments that fit both of their psychological and physical needs including but are not limited to: recognition from others, having more or less social interactions with others,seeking more knowledge to satisfy certain paths of curiosity.
In conclusion, both genes and environment contribute to the early involvement of temperament into traits. Young children who were rated by the parents as inhibited are more likely to rate themselves as highly inhibited as young adults. There is a strong link between genes and environments which is significantly shown in the critical transitioning period between childhood to adulthood. From other perspective, it could be the non-shared environments that may have substantial effects on the development of traits.
References:
Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., Poulton, R. (2003). Influence of Life Stress on Depression: Moderation by a Polymorphism in the 5-HTT Gene.Science,301(5631), 386–389.doi:10.1126/science.1083968
Feist, J., Feist, G. J., & Roberts, T.-A. (n.d.).Theories of personality.
Hampson, S. E. (2008). Mechanisms by which childhood personality traits influence adult well-being. Current Directions in Psychological Science,17(4), 264–268.doi:10.1111/j.1467-8721.2008.00587.x
McAdams, D. P. & Olson, B. D. (2010). Personality Development: Continuity and Change Over the Life Course. Annual Review of Psychology,61(1), 517–542.doi:10.1146/annurev.psych.093008.100507
Munafò, M. R., Clark, T. G., Moore, L. R., Payne, E., Walton, R., & Flint, J. (2003). Genetic Polymorphisms and Personality in Healthy Adults: A systematic reviewand meta-analysis.Molecular Psychiatry,8(5), 471–484.doi:10.1038/sj.mp.4001326
Muris, P. & Ollendick, T. H. (2005). The role of temperament in the etiology of child psychopathology. Clinical Child and Family Psychology Review,8(4), 271–289.doi:10.1007/s10567-005-8809-y
