Question

A researcher tests a group of identical twins raised together and a different group of identical twins who were separated at birth and raised in different environments. She finds that the \(1 Q\) scores of each pair of twins in the first group are more similar than are the 10 scores of each pair of twins in the second group. This difference between groups is the result of ________. a. genetic influences b. environmental influences c. neither environmental nor genetic influences d. an equal degree of environmental and genetic influences

Short answer

b. Environmental influences

Step-by-step solution

Identical twins have the same genetic makeup. Two groups of identical twins are studied, with one group being raised together in the same environment and the other group raised separately in different environments. The similarity in IQ scores within the first group of twins is found to be greater than in the second group of twins. #Step 2: Analyze the relationship between genetics and environment#

We need to consider how genetics and environmental factors influence IQ scores. Each of the given options suggests different causes for the observed difference in the IQ scores of the twins. a. Genetic influences: This option implies that the difference is caused solely by genetic factors. b. Environmental influences: This option implies that the difference is caused solely by environmental factors. c. Neither environmental nor genetic influences: This option implies that other factors, besides genetics and the environment, are responsible for the difference. d. An equal degree of environmental and genetic influences: This option implies that both genetics and environmental factors contribute equally to the difference in IQ scores. #Step 3: Eliminate the irrelevant options#

Since identical twins have the same genetic makeup, option a is not a relevant explanation for the difference in IQ scores. Option c can also be eliminated as the factors considered in this study are genetics and environment. #Step 4: Determine the cause of the difference#

The main difference between the two groups of twins is the environment they were raised in. Option b, environmental influences, seems to be the most plausible explanation for the observed difference in IQ scores between the two groups of twins, since they share the same genetics. So, the correct answer is: b. Environmental influences

Key concepts

Genetics and Intelligence

The relationship between genetics and intelligence is a core concept in understanding human cognitive abilities. Intelligence quotient, or IQ, is often used as a metric to measure intelligence, and research has consistently pointed towards a substantial genetic component.

Identical twins, who share 100% of their genetic code, provide a unique opportunity to explore this relationship. If genetics were the sole factor in determining IQ, we would expect identical twins to have identical IQ scores, regardless of their environment. However, studies have shown that while there is a high correlation in the IQ of identical twins, it is not perfect.

Heritability of Intelligence

Heritability refers to the proportion of variance in a trait, like IQ, explained by genetic differences. Studies estimate that genetics accounts for between 50% to 80% of the variability in IQ among individuals in a population. This suggests a substantial, but not exclusive, genetic influence on intelligence.

Improving clarity on this topic, it's vital to stress that heritability does not imply immutability. While someone may inherit certain genetic predispositions, their intelligence can still be significantly shaped by experiences, education, and environment.

Twin Studies Psychology

Psychologists have long been fascinated by studying twins to unravel the mysteries of human development. Twin studies in psychology focus on understanding how different factors affect the development of twins, especially those who are genetically identical.

The key feature of twin studies is comparing monozygotic (identical) twins with dizygotic (fraternal) twins and twins raised together versus those raised apart. Identical twins share their entire genome, while fraternal twins share about 50%, similar to ordinary siblings.

Natural Experiments

Twin studies are often referred to as natural experiments because they allow researchers to explore the effects of environment and genetics in a way that would be impossible to ethically orchestrate otherwise. For example, when identical twins are raised in different environments but still display remarkable similarities, it emphasizes the role of genetics. Conversely, differences between them can shed light on the impact of environmental factors.

To optimize comprehension here, it's essential to recognize that twin studies possess limitations, such as the assumption that environments for twins raised apart are entirely different, which may not always be true.

Nature Versus Nurture

The debate of nature versus nurture pertains to whether genetics ('nature') or environment ('nurture') plays a more significant role in shaping an individual's traits, including intelligence.

For many years, this debate was polarized with staunch advocates on either side. However, current understanding recognizes that both genetics and environment are interdependent, working together to influence the development of intelligence and other traits.

Interaction of Genetics and Environment

The interactive model suggests that genes provide a potential for intelligence, while the environment influences whether and how these genetic potentials are realized. For instance, access to education, nutrition, and stimulation during childhood all dramatically affect the development of a person's cognitive abilities.

By incorporating this nuanced perspective, students will grasp that the relationship between genetics and environment is not a zero-sum game; rather, it's akin to a collaborative tandem where both factors have a pivotal role in shaping intelligence. This integration of nature and nurture is critical for a comprehensive understanding of human intelligence development.