Summary. Research from developmental psychology is suggesting that personality traits are inherently stable across a lifetime. Some characteristics may explain actual behavior or predict future development. This post, however, examines the question related to how much of our underlying personality is “nature or nurture.” In summary, genetic factors are independent of age and sex influencing character stability during childhood, while environmental factors are largely contributing to changes during adolescence and adulthood. Child rearing, culture, and health are significantly contributing to the changes that occur besides natural constancies.
Genetic and Environmental Influences on Personality
Freud’s psychosexual mental processes attempting to explain the psychological development and Eysenck’s explanation looking after brain structures and functionality are opposed to personality theories that are more emphasizing the long-lasting influences of exogenous factors such as social adaptation and family environment factors (Briley & Tucker-Drob, 2014; Pulkkinen, 2009). Both genetic inheritance and external factors are preserving or changing personality (Briley & Tucker-Drob, 2014, p. 1303). According to Blatný, Millová, Jelínek, and Osecká (2015), personality traits related to malleability are predominantly at work in adolescence. The influence of the environment increases in adulthood (Bleidorn, Kandler, & Caspi, 2014). Consequently, the family environment and socio-economic factors have little influence on the genetically inherent personality traits (Hur, 2007). This, of course, does not mean that such influences may not shape behavior, as we all can observe how persons respond to the environment, albeit according to one’s characteristics. In other words, genetics is responsible for stability, and the environment for change in individual traits during late adolescence respectively early adulthood (Bratko & Butkovic, 2007). Macaskill, Hopper, White, & Hill (1994) found that Psychoticism and Neuroticism are mostly depending on genetic factors and not age and gender, while this wasn’t the case for extraversion.
(Environmental) Factors Causing Changes in Personality Traits
Personality traits are considered to be relatively consistent over time (Briley & Tucker-Drob, 2014). Environmental factors are estimated to influence change in psychological traits for up to 100% during adolescence to early adulthood (Bratko & Butkovic, 2007). Considering an extended period (10 – 12 years) genetic influences may contribute to change too to some extent (Bratko & Butkovic, 2007). According to Secular changes in personality (2013), it matters during what cultural époque one is living as 75-year-olds after 2000 are more extroverted than groups of the same age back in the 1970s. Traumatic experiences in childhood can be another source triggering personality change manifesting later on in life (Li, Wang, Hou, Wang, Liu, & Wang, 2014). The existence of illness during adolescence may also impact later psychological development and on the trait level that means that increased neuroticism in the form of ill feeling goes together with the health of individuals (Wilson, Wrench, McIntosh, Bladin, & Berkovic, 2009). Similarly, developmental psychology today can verify the presence of adult personality disorders already in childhood (Lenkiewicz, Srebnicki, & Bryńska, 2016).
Although personality psychology’s progress in longitudinal lifespan personality development studies (Bleidorn et al., 2014), further research is needed to understand better the interplay of genetic and environmental factors related to their influences on psychological trait development (Pulkkinen, 2009).
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