Nature vs. Nurture, More of the Blah, Blah, Blah...

Certainly there are people who seem to change little over the course of their lives, but it would be difficult, if not impossible, to negate the effects of environmental influences on them. Turkheimer, Haley, Waldron, D'Onofrio, and Gottesman (2003) found IQ in children was altered because of socioeconomic circumstances. Marmot (2004) determined "health follows a social gradient" (p. 1). In other words, the higher the status in life, the healthier the individual will be. Caspi, Taylor, Moffitt, and Plomin (2000) found children who live in poor neighborhoods show a significantly higher rate of behavioral and emotional issues that could not be explained by genetic influences.

Biology and an individual's genetics play a significant role in the creation of a general or prevailing temperament that works as a foundation, or a parameter upon which experiences and external and intrinsic forces exert their influence. Some biological or environmental circumstances exert far more influence than others. For example, a biological condition such as a severe genetic disorder might have a more significant effect on an individual than any environmental circumstance. Alternatively, an extreme environmental circumstance, such as severe poverty, might have more influence than any biological condition over the course of the lifespan. It would, however, seem far too simplistic to believe humans live in an experiential vacuum wherein experiences and other forces have little to no effect on individual development. Allemand, Zimprich, and Hertzog (2007) suggest evidence for both change and continuity across the lifespan, and although a prevailing personality may remain somewhat stable, even the stable aspects of individuals' personalities were at least partially characterized by change.

It seems like folly to try to exact a percentage of force exerted by nature or nurture. The interplay between genetically engineered traits, unique biology, and the usual and extraordinary influences on human development are complex, but dynamic in that both exert continuous influence across the lifespan (Berger, 2008). Allemand, Zimprich, and Hertzog (2007) found environmental influences affect personality cumulatively across the lifespan directly or are somewhat diffused by biological conditions. From a lifespan development perspective, the development of all people is fundamentally plastic and change is synonymous with growth and aging. Rutter (1997) contends nature and nurture are not as polarized as some contemporary research claims. Intrinsic characteristics may gain expression by virtue of biological programming as well as environmental forces (Rutter, 1997).

When perceiving humans as adaptive organisms, it is difficult, if not impossible to exclude change as a normal and expected mechanism of human existence (Allemand, Zimprich, & Hertzog, 2007). Sameroff (2010) poignantly proposed that whether nature or nurture bears more influence on development is a convoluted mix of psychological and cultural perspectives, social perceptions, and trends in research. Sameroff (2010) points out, for example, the relatively new abilities of technology in biological research has unearthed evidence on the nature side, that was previously unavailable. Consequently, recent research has focused on the genetic basis for behavior.



References:

Allemand, M., Zimprich, D., & Hertzog, C. (2007). Cross-Sectional Age Differences and Longitudinal Age Changes of Personality in Middle Adulthood and Old Age. Journal of Personality, 75(2), 323-358. doi: 10.1111/j.1467-6494.2006.00441.x

Berger, K. S. (2008). The developing person through the life span (7th ed.). New York: Worth Publishers.

Caspi, A., Taylor, A., Moffitt, T. E., & Plomin, R. (2000). Neighborhood Deprivation Affects Children's Mental Health: Environmental Risks Identified in a Genetic Design. Psychological Science, 11(4), 338-342. doi: 10.1111/1467-9280.00267

Kandler, C., Bleidorn, W., Riemann, R., Spinath, F. M., Thiel, W., & Angleitner, A. (2010). Sources of cumulative continuity in personality: A longitudinal multiple-rater twin study. Journal of Personality and Social Psychology, 98(6), 995-1008. doi: 10.1037/a0019558

Marmot, M. G. (2004). The status syndrome: How social standing affects our health and longevity. New York: Times Books.

Rutter, M. L. (1997). Nature-nurture integration: The example of antisocial behavior. American Psychologist, 52(4), 390-398. doi: 10.1037/0003-066X.52.4.390

Sameroff, A. (2010). A unified theory of development: A dialectic integration of nature and nurture. Child Development, 81(1), 6–22.

Turkheimer, E., Haley, A., Waldron, M., D'Onofrio, B., & Gottesman, I. I. (2003). Socioeconomic status modifies heritability of IQ in young children. Psychological Science, 14(6), 623-628. doi: 10.1046/j.0956-7976.2003.psci_1475.x