The impact of genes and environment on human development has been a controversial debate for a long time. On one hand, some people claim that nature is the sole determiner of human development; on the other hand, others assert that nurture is the only determiner of human development. In this paper, possible roles of both biology and environment on cognitive abilities will be discussed through providing a balanced interpretation based on the text and relevant readings from the class.
Nature’s influence is not limited to appearance but extends further than that. Studies have shown that people inherit cognitive abilities and temperament patterns from their parents. The new question in today's ...view middle of the document...
Correlations are highest when they are identical twins (as cited in Sigelman & Rider, 2009, p. 77).
Another study conducted with identical twins that are raised apart and reunited in later life demonstrated some personal traits and these personal traits’ relationship with environment and heredity (Grilo and Pogue-Geile, 1991, as cited in Sigelman & Rider, 2009). This study demonstrates a strong relatedness between appearances (the correlations for height is 0.86, weith is 0.73) and cognitive abilities (the correlation for alpha activity in brain is 0.80) of the twins; however, low correlation between personal interests (the correlations for occupational interest is 0.40 and religiosity is 0.49).
On the other hand, nurture which is another determiner of human development refers to the environmental factors that do not come from genes. Moreover, even though some research demonstrates a high correlation between intelligence abilities of family members, today, we know that some intelligence types change in lifespan. According to Sigelman and Rider (2009), the more a brain is exposed to intellectual stimulus, the stronger and more stable it stays through a lifespan. Therefore, environment can actually play a more important role than it is thought.
The research on twins to reveal the correlation between their cognitive abilities with their pairs conducted with mentally health people. However, some traumatic experiences may affect the cognitive abilities dramatically. For example, a highly intelligent person may lose his or her cognitive abilities upon a catastrophic accident.
In a study by Hanscombe, Trzaskowski, Haworth, Davis, Dale and Plomin (2012), 8716 twin pairs children’s IQ were tested at the age of 2, 3, 4 via the Parent Report of Children’s Abilities and the Bayley Scales of Infant Development. In the age of 7, 9, 10, 12 and 14 WISC-III UK and PI were utilized to test the twins’ IQ. The...