- A researcher finds that children with a genetic predisposition for irritability are more likely to be subjected to harsh, reactive parenting than children without this predisposition. The harsh parenting, in turn, is a risk factor for the development of later conduct problems. The initial link between the child's genetic makeup and the style of parenting they receive is a specific example of:
Answer: An evocative gene-environment correlation.
The correct answer is C. This scenario describes an evocative gene-environment correlation, where the child's genetically-influenced trait (irritability) elicits a specific response (harsh parenting) from the environment. A is incorrect because the scenario doesn't state that the effect of harsh parenting differs by genotype, only that the likelihood of receiving it does. This is a subtle but critical distinction. B is incorrect because the parenting style is a reaction to the child, not an independent environment provided by parents who also happen to pass on 'irritability' genes. D is too specific and mechanistic; the overarching phenomenon described is evocative rGE.
- According to the 'range of reaction' principle, an individual's genes for a particular trait, such as intelligence:
Answer: set the upper and lower boundaries of potential for that trait, with the environment determining the specific outcome within those boundaries.
The correct answer is C. The range of reaction concept posits that one's genotype establishes a range of possible responses to different kinds of life experiences. For example, genes may set a potential IQ range, and environmental factors like nutrition, schooling, and stimulation will determine where in that range the individual's IQ will fall. A describes a purely deterministic genetic view. B contradicts the idea of a genetically determined range. D describes active gene-environment correlation, which is a different concept.
- A large-scale study finds that individuals with a specific genetic variant are no more likely to experience depression than the general population. Similarly, experiencing a single major life stressor only slightly increases depression risk for most people. However, individuals who possess the genetic variant and experience a major life stressor show a dramatically elevated risk of developing major depressive disorder. This pattern of results provides strong support for the:
Answer: Diathesis-stress model.
The correct answer is C. The diathesis-stress model posits that a pre-existing vulnerability (diathesis), often genetic, is triggered by an external stressor, leading to a negative outcome like a psychological disorder. In this case, the genetic variant is the diathesis and the life stressor is the trigger. A is incorrect as it deals with the potential range of a trait. B is incorrect as there is no evidence the gene causes people to experience more stressors. D, canalization, refers to the degree to which development is buffered from environmental influences, which is the opposite of what is shown.
- Imagine a hypothetical society where from birth, all children are provided with identical, optimal nutrition, education, and social support, effectively minimizing environmental variation. In this society, what would be the most likely consequence for the heritability of intelligence and the average level of intelligence?
Answer: Heritability would be very high, and the average level of intelligence would also be high.
When you encounter questions about heritability, remember that heritability measures the proportion of trait variation in a population that's due to genetic differences, not the absolute contribution of genes to a trait. This concept is crucial because heritability depends heavily on environmental conditions.
In this hypothetical society with optimal and uniform environments, you'd see both high heritability and high average intelligence. Here's why: When environmental factors are minimized and optimized, nearly all remaining variation in intelligence would stem from genetic differences between individuals. This pushes heritability toward 1.0 (very high). Simultaneously, because everyone receives optimal nutrition, education, and support, the average intelligence level would be much higher than in typical populations where many people lack these advantages.
Looking at the wrong answers: Option B incorrectly suggests heritability would be low when environmental variation is minimized—this is backwards thinking. Option C gets heritability right but misses that optimal conditions would boost average intelligence above typical levels. Option D is wrong on both counts, incorrectly predicting both low heritability and low intelligence when the opposite would occur.
The key insight is that heritability and average trait levels can move in the same direction. Optimal environments don't reduce genetic influence—they reveal it more clearly by removing environmental noise while simultaneously boosting everyone's performance.
Study tip: Remember that heritability is about the relative contribution of genes to variation within a specific population under specific conditions. When environments improve and become more uniform, heritability typically increases even as average performance rises.
- An adoption study is conducted to disentangle the influences on verbal ability. It finds that the environment provided by adoptive parents significantly influences a child's verbal scores. This study design is particularly effective at isolating the impact of the rearing environment by removing which specific effect that is typically present in biological families?
Answer: Passive gene-environment correlation, where parents provide both genes for verbal ability and a corresponding home environment.
The correct answer is B. In biological families, parents provide both genes and the environment, which are often correlated. For example, parents with high verbal ability (genes) are also likely to have many books in the home (environment). This is passive rGE. Adoption studies separate these influences because the adoptive parents provide the environment but not the genes. The question asks what influence is removed by this design, which is the passive correlation between the parents' genes and the environment they provide.
- The results of the investigation are displayed in the line graph. The pattern of results depicted in the graph strongly suggests that:
Answer: the s allele of the 5-HTTLPR gene confers a genetic vulnerability to the depressive effects of environmental stress.
The correct answer is C. The graph shows a classic gene-environment interaction. The effect of stress (x-axis) on depressive symptoms (y-axis) is much stronger for individuals with one or two copies of the s allele, particularly the s/s genotype. This indicates that the s allele makes individuals more susceptible to the negative psychological impact of stress. A is incorrect because the effect of stress clearly depends on genotype. B is incorrect because at low levels of stress, individuals with the s/s genotype do not have elevated depression scores. D suggests an active gene-environment correlation, which is a different concept and is not depicted in the graph.
- A new drug is tested for anxiety. For patients with a common genetic profile (Profile A), the drug works moderately well. For patients with a rare genetic profile (Profile B), the drug is extremely effective. However, when given a placebo, patients with Profile B experience a significant worsening of their anxiety, while Profile A patients show a slight improvement. The response of Profile B patients to both the drug and the placebo best exemplifies:
Answer: Differential susceptibility.
The correct answer is D. Differential susceptibility suggests that some individuals are more malleable or sensitive to their environments, for better and for worse. Profile B patients show this pattern: they have an extremely positive reaction to a positive environment (the drug) and an extremely negative reaction to a neutral or negative environment (the placebo). A, the diathesis-stress model, would only predict the negative outcome in a stressful context, not the exceptionally positive outcome in a supportive one. B is too simple; it captures the drug response but not the paradoxical placebo response. C is irrelevant as patients did not choose their treatment.
- Researchers observe that infants with a genetically influenced predisposition for an easy-going temperament tend to receive more responsive and positive caregiving compared to infants with a more difficult temperament. This occurs even when parents consciously try to treat all infants similarly. This pattern, where the child's innate characteristics shape the environment they experience, is known as:
Answer: Evocative gene-environment correlation.
The correct answer is B. Evocative (or reactive) gene-environment correlation occurs when an individual's genetically influenced traits elicit or evoke specific responses from the environment (in this case, from caregivers). The infant's easy-going nature evokes positive caregiving. A is incorrect because the environment is a reaction to the child, not one that is passively provided. C is incorrect because while such experiences could lead to epigenetic changes, the phenomenon itself is best described as evocative rGE. D is incorrect as there is no mention of a negative outcome or disorder being triggered by stress.
- A study on rats demonstrates that extensive maternal licking and grooming of pups alters the methylation patterns on the pups' glucocorticoid receptor gene. This change leads to a less pronounced physiological stress response in adulthood. A cross-fostering part of the study shows that pups of low-licking mothers raised by high-licking mothers exhibit the same positive outcomes. This result is a primary example of:
Answer: An epigenetic effect, where behavior influences gene expression without altering the DNA sequence.
The correct answer is A. This scenario describes epigenetics, where an environmental factor (maternal behavior) causes a change in gene expression (via methylation) that affects a phenotype (stress response). The cross-fostering design is crucial because it rules out purely genetic transmission (B) and passive gene-environment correlation (C) by showing that the rearing environment, not the biological parentage, is the causal factor. D is incorrect because the study shows that the environment can, in fact, alter the phenotypic outcome related to stress.
- A longitudinal study tracks children with a genetically influenced trait of high sensation-seeking. The study finds that while these children are average in their activity choices in early childhood, by their late teens they are significantly more likely than their peers to pursue activities like rock climbing, snowboarding, and motorcycle racing. This developmental pattern is a primary example of:
Answer: Active gene-environment correlation (niche-picking).
The correct answer is C. Active gene-environment correlation, or niche-picking, occurs when individuals' genetic predispositions lead them to actively select environments that are compatible with those predispositions. In this case, the sensation-seeking trait leads individuals to choose high-sensation activities. A is incorrect because the scenario is not about the children's trait eliciting a response from others. B is incorrect as it relates to environments provided by parents. D is incorrect because it is not about differential susceptibility to an environment, but rather the active selection of one.
- In Country A, access to high-quality nutrition and education is highly unequal. In Country B, all citizens have access to the same excellent, standardized nutrition and education. A behavioral geneticist plans to estimate the heritability of cognitive ability in large samples from both countries. Which outcome should she predict?
Answer: The heritability of cognitive ability will be significantly higher in Country B than in Country A.
The correct answer is A. Heritability is the proportion of total phenotypic variance that is due to genetic variance (Vg​ / Vp​). In Country B, the environmental variation is minimized. When environmental variance decreases, genetic variance accounts for a larger proportion of the total variance, leading to a higher heritability estimate. B gets the logic backward. C is incorrect because heritability is a population-specific statistic, not a biological constant. D is incorrect; providing a high-quality environment for all is likely to raise the average cognitive ability. - Monozygotic twins were raised together in the same home, yet as adults, one develops a clinical anxiety disorder while the other does not. Given that they share 100% of their genes and a very similar upbringing, this difference in outcome is most likely attributable to:
Answer: Non-shared environmental influences that created unique experiences for each twin.
The correct answer is C. Non-shared environmental influences refer to the unique experiences that affect one twin but not the other, even when raised together (e.g., a different group of friends, a specific illness, a different relationship with a teacher). These influences are thought to be a major reason why MZ twins are not phenotypically identical. A is a general statement that doesn't explain this specific case. B is a possibility but is a far less common explanation in behavioral genetics than non-shared environment. D is genetically impossible, as MZ twins are identical.
- An adoption study finds that the correlation for the personality trait of extraversion is r = .30 between adoptees and their biological parents, with whom they did not live. The correlation is r = .05 between the same adoptees and their adoptive parents. What is the most supportable conclusion?
Answer: Genetic factors appear to play a more significant role than shared environmental factors in the variation of extraversion.
The correct answer is B. The correlation between adoptees and their biological parents (r = .30) reflects genetic influence, while the correlation with adoptive parents (r = .05) reflects shared environmental influence. Because the genetic correlation is substantially larger than the environmental one, it suggests a more significant role for genetic factors in the observed differences in extraversion. A is incorrect because squaring the correlation (r2) estimates variance accounted for, and even then it's an oversimplification. C is incorrect because correlation coefficients are not direct heritability estimates. D cannot be concluded, as the study does not provide the data needed to quantify the impact of the non-shared environment relative to genetics. - A study finds that individuals with a specific allele for a dopamine receptor gene are significantly more likely to develop a substance use disorder, but only if they experienced pronounced peer rejection during adolescence. Individuals with the same allele who reported strong peer support showed no increased risk compared to the general population. Which concept best explains this finding?
Answer: Gene-environment interaction, where the effect of the genetic predisposition on the outcome is dependent on a specific environmental factor.
The correct answer is D. This is a classic example of a gene-environment interaction (GxE), where the influence of a gene on a phenotype (substance use disorder) depends on an environmental condition (peer rejection). The gene's effect is not uniform across all environments. A is incorrect because the scenario does not mention the role of parents. B and C are incorrect because the scenario does not suggest that the gene causes behaviors that evoke rejection or lead to seeking out such environments; rather, it describes a differential susceptibility to an environmental stressor.
- A study on monozygotic (MZ) and dizygotic (DZ) twins finds concordance rates for a specific psychological disorder to be 55% for MZ twins and 20% for DZ twins. Which of the following is the most valid interpretation of these findings?
Answer: There is a substantial genetic component to the disorder, but non-genetic factors also play a critical role in its expression.
The correct answer is D. The fact that the MZ concordance rate (55%) is much higher than the DZ rate (20%) points to a significant genetic influence. However, the fact that the MZ rate is not 100% indicates that environmental factors must also be involved, as genetically identical individuals do not always share the disorder. A is incorrect because a purely genetic disorder would have a 100% MZ concordance rate. B is a common error; concordance rates are not the same as heritability estimates. C is incorrect because the large difference between MZ and DZ rates strongly argues against the shared environment being the primary cause.
- A large-scale study in a Western country estimates the heritability of IQ to be approximately 0.50. Based on this statistical estimate, which of the following is the most accurate conclusion?
Answer: In the population studied, about half of the measured variation in IQ scores can be attributed to genetic differences among individuals.
The correct answer is B. Heritability is a population statistic that estimates the proportion of phenotypic variance (i.e., observed differences among individuals) in a trait that can be attributed to genetic variance. It does not apply to a single individual. A is the most common misinterpretation of heritability. C is incorrect; reducing environmental variation would cause heritability to increase, as genes would account for a larger proportion of the remaining differences. D is incorrect because heritability says nothing about the malleability of a trait or whether the population mean can be shifted by environmental factors.
- A researcher studies children with a genetic marker for high emotional reactivity. Children with this marker who are raised in highly supportive families become exceptionally empathetic and socially competent. However, children with the same marker raised in harsh, neglectful families show high levels of aggression. Children without the marker show average outcomes regardless of their family environment. This genetic marker's function is best captured by which concept?
Answer: Differential susceptibility, where the marker increases sensitivity to both positive and negative environmental influences.
The correct answer is B. Differential susceptibility (also known as the 'orchids and dandelions' model) proposes that certain genetic factors make individuals more susceptible to environmental influences in general, for better and for worse. This contrasts with the diathesis-stress model (A), which only focuses on the negative outcome in a negative environment and does not account for the exceptionally positive outcomes in a supportive one. C is incorrect because the children are not described as choosing their environments. D is incorrect because heritability is a population statistic, not a description of a specific gene's interactive function.
- Maya's parents are professional musicians who passed on genes associated with musical talent and also raised her in a home filled with music and instruments. As a child, her innate aptitude led her teachers to give her special attention and more challenging pieces. As a teenager, she now independently chooses to join the school orchestra, a jazz band, and a competitive summer music camp. Which sequence correctly identifies the primary gene-environment correlations at play during these three phases of her life?
Answer: Passive, evocative, active.
The correct answer is B. The sequence follows a typical developmental progression. First, 'passive' rGE is at play, as her parents provide both genes and a musical environment. Second, 'evocative' rGE occurs as her talent elicits a special response from her teachers. Third, 'active' rGE (niche-picking) occurs as she begins to make her own choices to seek out environments that fit her genetic predispositions. D is incorrect because 'interactive' refers to GxE, not rGE.
- The researcher presents the results in the graph below. Based on the graph shown, which phenomenon is illustrated?
Answer: A gene-environment interaction, where the effectiveness of the program depends on the child's genotype.
The correct answer is C. The graph shows a classic gene-environment interaction. The effect of the environment (the educational program) is different for the two genotypes. Specifically, the new program provides a large benefit for children with Genotype A but only a minimal benefit for children with Genotype B. There is not a main effect of genotype only (A), because their scores are nearly identical in the standard curriculum. There is not a main effect of environment only (B), because the program's benefit is not uniform. D is incorrect as this is an experimental design that cannot demonstrate a passive correlation.
- A study of adult men who survived a severe famine during their early childhood finds they have specific epigenetic marks on genes related to metabolism. Later, their own children, who were never exposed to famine, are found to have a higher-than-average incidence of metabolic syndrome. Which is the most likely mechanism to explain the children's increased risk?
Answer: Transgenerational epigenetic inheritance, where environmental effects on gene expression are passed to offspring.
This question tests your understanding of epigenetics and how environmental factors can affect gene expression across generations. When you encounter scenarios involving environmental effects on parents that somehow impact their offspring who weren't exposed to the same environment, think about epigenetic mechanisms.
The key evidence here is that famine-exposed fathers have specific epigenetic marks on metabolism genes, and their unexposed children show metabolic problems. This points to transgenerational epigenetic inheritance, where environmental stressors can alter gene expression patterns that are then passed to offspring through epigenetic modifications in sperm or egg cells. The famine didn't change the DNA sequence itself, but rather changed how genes are expressed through mechanisms like DNA methylation or histone modifications. Answer A correctly identifies this mechanism.
Answer B incorrectly assumes the children's problems stem from shared diet, but the question specifies the children were never exposed to famine conditions. Answer C misunderstands the scenario by invoking "thrifty genes" - actual genetic variants that predispose to metabolic issues. However, the question describes epigenetic marks, not genetic mutations, and the mechanism isn't about passing on both genes and behaviors. Answer D suggests direct genetic mutations, but epigenetic marks are modifications to gene expression, not changes to the underlying DNA sequence.
Remember that epigenetic inheritance is an emerging area in psychology and biology. When you see questions about environmental effects on parents influencing unexposed offspring, especially with mentions of "epigenetic marks," think transgenerational epigenetic inheritance rather than traditional genetic or environmental explanations.
