Question 1

The only thing that can keep identical twins reared together from resembling each other on an attribute is nonshared environmental influences. Therefore, it makes sense that we could estimate how much nonshared environment (NSE) contributes to the attribute as follows: NSE =

Accepted Answer

The formula for estimating nonshared environment contribution is 1 - r _{identical twins}. This is because identical twins share all their genes, so any differences in their attributes must be due to nonshared environmental influences. The correlation coefficient (r) between identical twins is used to estimate the heritability of a trait, but subtracting it from 1 gives an estimate of the nonshared environment contribution to the trait.

Question 2

If an investigator conducted a twin study of intelligence with African?-American children, finding that the heritability of IQ in this sample was +.75, she could conclude that

Accepted Answer

Heritability estimates, such as +.75, indicate the proportion of variance in IQ within the studied sample that can be attributed to genetic differences. This does not mean that 75% of an individual's IQ is due to genes, nor does it imply that the heritability will be the same in different environments or populations. Heritability is a population concept, not an individual one, and is specific to the particular group and environment studied.

Question 3

Ben and Sarah are siblings. Their parents play with and regularly encourage them to play "intellectual" games such as chess and concentration. Ben hates these activities, while Sarah loves them. This different reaction to playing intellectual games is perfectly understandable from the perspective of passive genotype/environment correlations if

Accepted Answer

Passive genotype/environment correlations occur when parents provide both genes and environment that are correlated with each other. In this scenario, the parents are providing the intellectual games as well as the genes for intellectual ability. If Ben is an adopted child, he may not have inherited the genes for strong intellectual abilities, which would explain his dislike of these games. On the other hand, Sarah may have inherited these genes, which would explain her enjoyment of the games. The other choices do not necessarily explain these differences in preferences for intellectual games.

Question 4

Scarr and McCartney propose the notion of _____ genotype/environment correlations to explain how the genetically-influenced attributes we possess might shape development by influencing other people's reactions to us.

Accepted Answer

Scarr and McCartney propose the notion of evocative genotype/environment correlations, which suggest that our genetically influenced attributes shape development by influencing other people's reactions to us.

Question 5

Shared environmental influences are most likely to shape personality

Accepted Answer

Shared environmental influences are most likely to shape personality for attributes on which parents strive to treat children alike. This means, for example, parents who value academic achievement and provide equal opportunities for all of their children to succeed academically are more likely to influence their children's personality in this area through shared environmental factors such as education resources and encouragement.

Question 6

Twin studies investigating the heritability of mental disorders reveal that _____.

Accepted Answer

Twin studies show that while there is a genetic component to mental disorders, identical twins can still be discordant, indicating environmental factors also play a significant role.

Question 7

Bailey and his associates found that the concordance rate for homosexuality was greater among identical twins (52%) than among fraternal twins (22%). From these data, we can conclude that

Accepted Answer

The higher concordance rate in identical twins compared to fraternal twins suggests that there is a genetic influence on homosexuality. However, it does not necessarily mean that it is genetically determined or that environment plays little part in determining homosexuality.

Question 8

If we were to study the shyness of adopted children and find that they resemble both their adoptive parents (r = +.40) and their birth parents (r = +.40) on this attribute, we might conclude that

Accepted Answer

The resemblance of adopted children to both their adoptive parents and their birth parents in terms of shyness, with a correlation coefficient of +.40 in both cases, suggests that both genetic factors (from the birth parents) and environmental factors (from the adoptive parents) play a role in the development of shyness. This supports the idea that shared environment (the environment provided by the adoptive parents) has a meaningful impact on the development of shyness.

Question 9

We know that individual genotypes play a part in the development of an attribute if

Accepted Answer

C) Adopted children showing greater resemblance to their birth parents than to their adoptive parents indicates that genetics (individual genotypes) play a significant role in the development of that attribute. This is because the adoptive environment is similar for both sets of children, so differences in resemblance are more likely due to genetic factors.

Question 10

Scarr and McCartney propose that the rearing environment that biological parents provide is influenced to some extent by their genes and is therefore correlated with the child's genotype. They called this type of influence a(n):

Accepted Answer

Scarr and McCartney proposed three main types of genotype/environment correlations: passive, evocative, and active. Passive genotype/environment correlations occur when biological parents provide both genes and the rearing environment and are therefore correlated with the child's genotype. This is the best description for the option C, passive genotype/environment correlation.

Question 11

If individuals reared together are as similar on an attribute as are equally related individuals reared apart, then we can conclude that the attribute is

Accepted Answer

If individuals reared together are as similar on an attribute as are equally related individuals reared apart, then the attribute is affected very little by shared environmental influences, as the similarity cannot be attributed to their shared environment (since those reared apart do not share the same environment). This would suggest that genetic factors play a greater role in determining the attribute.

Question 12

To estimate the heritability of a particular attribute from twin data, a researcher would have to know

Accepted Answer

To estimate the heritability of a particular attribute from twin data, researchers compare the correlation between identical (monozygotic) twins reared together with the correlation between fraternal (dizygotic) twins reared together. Identical twins share 100% of their genes, while fraternal twins share, on average, 50% of their segregating genes. By comparing these correlations, researchers can estimate the extent to which genetic factors contribute to the variance in the trait of interest, which is the essence of heritability.

Question 13

To estimate the influence of shared environmental influence on an attribute one would need to know

Accepted Answer

The answer of To estimate the influence of shared environmental...

Question 14

Behavioral geneticists use heritability coefficients _____.

Accepted Answer

Heritability coefficients are used to estimate the extent to which genetic factors contribute to individual differences in a trait, such as intelligence or personality. They are not used to determine whether a trait is solely inherited, as environmental factors can also play a role. Therefore, choice B is incorrect. However, by estimating the heritability of a trait, behavioral geneticists can determine whether there is likely to be a genetic basis for individual differences, which may prompt further investigation into the specific genes involved. Thus, choice A is correct. Finally, choice C is incorrect as it inaccurately suggests that both A and B are correct.

Question 15

If we find that identical twins raised together are notably dissimilar on an attribute like IQ, that is known to be genetically influenced, we can conclude that

Accepted Answer

The answer of If we find that identical twins raised...

Question 16

Nonshared environmental influences

Accepted Answer

Nonshared environmental influences are those that differ between siblings, leading to differences in personality traits, attitudes, and behaviors. These influences can include differential parenting, unique life experiences, and different peer groups. While genetics certainly play a role in personality development, nonshared environmental influences are an important factor in explaining why siblings often have distinct personalities despite growing up in the same household.

Question 17

The fact that identical twins are often discordant with respect to mental illnesses such as schizophrenia suggests that

Accepted Answer

The fact that identical twins, who share the same genetic makeup, can still have different outcomes with respect to mental illnesses suggests that environmental factors play a significant role in the development of these illnesses. This is supported by numerous studies on the heritability of mental illnesses such as schizophrenia, which indicate that genetic factors alone cannot fully account for the wide range of observed variations in the disorder.

Question 18

A capacity for empathy and empathic concern

Accepted Answer

Empathy and empathic concern are influenced by both genetic factors (heritable) and environmental factors, suggesting that they can be considered both inherited and heritable attributes.

Question 19

According to behavioral geneticists, the environmental influences that contribute most heavily to the developing personality are

Accepted Answer

Behavioral geneticists argue that the non-shared environment (aspects of the home environment that family members do not share) contributes most heavily to the developing personality, emphasizing the unique experiences of each individual within the same family.

Question 20

If the correlation for pairs of identical twins on Trait X is +.80 and the correlation for pairs of fraternal twins on this same trait is +.70, we could conclude that this attribute is most heavily influenced by

Accepted Answer

The higher correlation in identical twins compared to fraternal twins suggests that shared environmental influences play a significant role, as both types of twins share the same environment but differ in genetic similarity.

Quiz 3: Recent Perspectives on Social and Personality Development