Question 1

Studies comparing the similarity of identical and fraternal twins who are raised together and apart are especially informative because

Accepted Answer

These studies allow researchers to disentangle the effects of environment and genetics on various traits and behaviors by comparing the similarities between identical twins (who share nearly all their genes) and fraternal twins (who share about half their genes), both when raised together and apart. This comparison provides insights into how much variation in a trait is due to genetic factors versus environmental factors.

Question 2

Barbara and Brenda are identical twins who were adopted at birth and raised by two different families. Andy and Andrew are identical twins raised together by their biological parents. When the four children entered high school they took an IQ test. Barbara and Andy each had scores of 110, while Brenda's IQ was measured at 120 and Andrew scored 108. These results support which of the following conclusions?

Accepted Answer

The variation in IQ scores among the identical twins raised in different environments (Barbara and Brenda) and the slight difference in scores between Andy and Andrew, who were raised together, suggest that both genetics and environment play roles in shaping intelligence.

Question 3

Researchers who believe in the concept of a reaction range are most likely to argue that intelligence is

Accepted Answer

The concept of a reaction range suggests that genetics sets the potential range for an individual's intelligence, but the environment determines where within that range the individual's intelligence will fall. Thus, intelligence is seen as the product of the interaction between genetics and the environment.

Question 4

The reaction range principle suggests that genetics sets the upper and lower limits for a trait and _________ indicates where in that range a particular trait will fall.

Accepted Answer

The reaction range principle posits that while genetics determines the potential range (upper and lower limits) of a trait, the environment influences where within this range the trait will actually manifest.

Question 5

If intelligence was completely determined by genetics, then which set of correlations would be the same?

Accepted Answer

The answer of If intelligence was completely determined by genetics,...

Question 6

A genetically determined trait may have an upper and lower limit, and the environment may determine the exact level of the trait that ultimately gets expressed. This is referred to as the concept of ______.

Accepted Answer

The concept of "reaction range" refers to the range of possible phenotypes (expressions of a trait) that can result from a given genotype, depending on environmental conditions. This means that while genetics set the potential limits of a trait, the environment influences where within those limits the trait will actually fall.

Question 7

The heritability coefficient is highest for which of the following human characteristics?

Accepted Answer

Height has a high heritability coefficient, indicating that genetic factors play a significant role in determining an individual's height. Studies have shown that genetics account for a large proportion of the variation in height among individuals.

Question 8

Adoption studies have found that people with schizophrenia are

Accepted Answer

Adoption studies have shown that individuals with schizophrenia are more similar to their biological parents than to their adoptive parents, indicating a genetic component to the disorder.

Question 9

Scott and Shawn are identical twins raised together, whereas Tammy and Tracey are identical twins raised apart. Scott and Shawn are more similar on IQ than are Tammy and Tracey. This finding

Accepted Answer

The finding that Scott and Shawn, who were raised together, are more similar in IQ than Tammy and Tracey, who were raised apart, suggests that environmental factors play a role in determining IQ, thus ruling out a purely genetic explanation.

Question 10

What do we currently know about the specific sizes of reaction ranges for individuals?

Accepted Answer

The answer of What do we currently know about the...

Question 11

One problem with studying identical and fraternal twins raised together or apart is that

Accepted Answer

Identical twins raised together may be treated more similarly than fraternal twins, which could lead to greater behavioral similarity due to environmental factors rather than genetic ones.

Question 12

An adoption study examined the heritability of criminal behaviour in boys adopted at a young age. The level of boys' criminality was greatest when _______.

Accepted Answer

The level of boys' criminality is greatest when both biological and adoptive fathers had criminal records, suggesting that both genetic factors (from biological parents) and environmental influences (from adoptive parents) contribute to the development of criminal behavior.

Question 13

The heritability coefficient for intelligence is.50. This means that

Accepted Answer

The heritability coefficient for intelligence (or any trait) being .50 suggests that 50 percent of the variation in intelligence within a group of people can be attributed to genetic factors. This coefficient does not directly address the variation between groups or the proportion of an individual's intelligence that is due to genetics.

Question 14

Twin studies have found that some psychological traits, such as intelligence, have a notable genetic contribution. This can be concluded from what evidence?

Accepted Answer

The correct answer is C because identical twins share 100% of their genes, and if they show greater similarity in psychological traits even when raised apart compared to fraternal twins (who share only about 50% of their genes), it suggests a significant genetic contribution to those traits.

Question 15

An adoption study examining the heritability of criminal behaviour found that people who had biological parents and adoptive parents who both had criminal records were the most likely to be criminals themselves. This example was presented to demonstrate

Accepted Answer

This example illustrates the interaction between genetic factors (biological parents with criminal records) and environmental factors (adoptive parents with criminal records) in influencing criminal behavior, demonstrating how both sets of factors can work together to shape outcomes.

Question 16

Although genetic factors are considerably important, they appear to account for about a certain percentage of the IQ variation within a group. This percentage ranges from _________________.

Accepted Answer

Genetic factors are estimated to account for about 50 to 70 percent of IQ variation within a group, with the remainder influenced by environmental factors and their interactions with genetic predispositions.

Question 17

Keith and Kirk are identical twins who were separated at birth and raised in different parts of the country in different environments. When as adults they were reunited, researchers compared them on several psychological characteristics. Compared to identical twins that have been raised together, Keith and Kirk probably have

Accepted Answer

Identical twins raised apart, like Keith and Kirk, tend to have fewer characteristics in common compared to those raised together due to the influence of different environments on their development.

Question 18

The heritability coefficient is used to estimate

Accepted Answer

The heritability coefficient is a measure used in genetics to estimate the proportion of observed variation in a particular trait (as seen in a population) that can be attributed to inherited genetic factors, rather than environmental influences.

Question 19

Though presently there is no quantifiable way to determine the reaction ranges of various intelligence-related traits, research on environmental enrichment programs and adoption studies suggest that the ranges could be

Accepted Answer

The answer of Though presently there is no quantifiable way...

Question 20

In general, which statement below best summarizes the outcome of the role of heredity and environment as they affect intelligence

Accepted Answer

Heredity and environment both play crucial roles in determining intelligence, and their interaction influences the development and expression of intellectual abilities. Genetics provides the potential, while the environment can either foster or hinder the realization of this potential.

Quiz 4: Genes, Evolution, and Behaviour