Behavioral Genetics and Gene–Environment Interaction (7A)
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MCAT Psychological and Social Foundations › Behavioral Genetics and Gene–Environment Interaction (7A)
A study examined gene–environment correlation in sports participation. Adolescents were genotyped for a variant associated with higher endurance capacity. The school offered multiple sports with open tryouts and no fees. Researchers found that students with the endurance-associated genotype were more likely to join cross-country or soccer rather than non-endurance clubs, and they reported enjoying long-duration exercise more. Participation predicted improved cardiovascular fitness at follow-up. The authors noted that genetic differences may have influenced selection into certain activities, increasing exposure to training environments.
What prediction is most consistent with gene-environment correlation as described?
Training should alter the DNA sequence of the endurance gene, producing the endurance-associated genotype.
If sports participation is assigned randomly, genotype differences in the types of activities chosen should decrease.
Fitness gains should occur only for students without the endurance-associated genotype.
Enjoyment of endurance exercise should be unrelated to genotype because preferences are purely environmental.
Explanation
This question evaluates gene–environment correlation in behavioral genetics, where genotypes influence sports selection. Active correlation involves choosing matching activities, enhancing fitness. The vignette links endurance genotype to specific sports. Choice D predicts decreased differences with random assignment. Choice B suggests genotype change from training. Test via forced participation. Differentiate by selection mechanisms.
Researchers conducted a twin study on language development in bilingual homes. Monozygotic (MZ) and dizygotic (DZ) twins were assessed at age 5 on vocabulary in the community language. Some families used a bilingual environment at home (regular use of two languages), while others used only the community language. In monolingual homes, MZ twins were more similar than DZ twins in vocabulary. In bilingual homes, average vocabulary in the community language was slightly lower, and MZ–DZ differences in similarity were smaller. The authors suggested the language environment altered the extent to which genetic differences explained variability in vocabulary.
Based on the vignette, which conclusion about genetic predisposition and environment is supported?
Because twins share a household, vocabulary differences must be caused only by measurement error.
Lower average vocabulary in bilingual homes proves genes are irrelevant to language development.
Smaller MZ–DZ differences in bilingual homes show that twins’ genes have changed due to language exposure.
The bilingual home environment may reduce the relative impact of genetic differences on community-language vocabulary.
Explanation
This question assesses gene–environment interaction in behavioral genetics using twins, with bilingualism moderating vocabulary heritability. Bilingual environments can attenuate genetic differences in language. The vignette indicates smaller MZ–DZ gaps in bilingual homes. Choice A supports reduced genetic impact. Choice B overclaims irrelevance of genes. Compare similarities by language exposure. Interactions alter heritability contexts.
Researchers conducted a twin study on social media use and body dissatisfaction. Monozygotic (MZ) and dizygotic (DZ) twin pairs were surveyed at age 17. Some attended schools with a strict phone-free policy during the school day, while others attended schools without such restrictions. In unrestricted schools, MZ twins were noticeably more similar than DZ twins in body dissatisfaction scores. In phone-restricted schools, average body dissatisfaction was lower, and MZ–DZ differences in similarity were smaller. The authors argued that limiting exposure reduced the extent to which genetic differences in susceptibility were expressed.
Based on the vignette, which conclusion about genetic predisposition and environment is supported?
Phone restriction proves body dissatisfaction is caused entirely by school policy rather than genes.
Phone restriction may dampen the expression of genetic susceptibility to body dissatisfaction.
School phone policies change twins’ zygosity classification over time.
Greater MZ similarity in unrestricted schools indicates that environment plays no role in body dissatisfaction.
Explanation
This question evaluates gene–environment interaction in behavioral genetics via twins, showing phone restrictions moderate body dissatisfaction heritability. Environmental limits can attenuate genetic expression, reducing twin similarity differences. The vignette illustrates smaller MZ–DZ gaps in restricted schools with lower dissatisfaction. Choice A supports this, indicating restrictions dampen genetic susceptibility. Choice B is a distractor, overclaiming environmental causation by ignoring genetic roles. For similar items, compare heritability estimates across conditions. Remember, interactions appear when protective environments shrink genetic variance.
A study explored gene–environment correlation in risk-taking. Young adults were genotyped for a variant associated with higher sensation seeking. Participants reported their typical weekend activities and peer networks. Individuals with the sensation-seeking–associated genotype were more likely to report friends who enjoyed high-adrenaline activities (e.g., cliff diving) and were more likely to attend events where alcohol was present. The study noted that genetic predispositions may shape the social environments people select, which in turn influence risk-taking outcomes.
What prediction is most consistent with gene-environment correlation as described?
Genotype should be unrelated to peer networks because peers are entirely determined by chance.
Attending alcohol-present events should change participants’ genotype toward lower sensation seeking.
If access to high-adrenaline activities is restricted for everyone, genotype differences in exposure to those settings should decrease.
Risk-taking should occur only among individuals without the sensation-seeking–associated genotype.
Explanation
This question examines gene–environment correlation in behavioral genetics, where sensation seeking shapes social environments. Correlation involves selecting risk-aligned peers and activities. The vignette links genotype to high-adrenaline friends and events. Choice D predicts decreased differences with restrictions. Choice B suggests event changes genotype. Predict under restricted access. Identify if predispositions drive selection.
A longitudinal study explored gene–environment correlation in musical training. Children were genotyped for a polygenic score associated with rhythmic perception. Families were offered subsidized music lessons, but enrollment required parents to sign up and bring the child weekly. Researchers found that children with higher rhythmic-perception scores were more likely to request lessons, and their parents reported more frequent attendance at live music events. After a year, lesson attendance predicted improved rhythm tests. The authors noted that genetic differences may have influenced exposure to music-rich environments through both child preference and parental behavior.
What prediction is most consistent with gene-environment correlation as described?
Parents’ attendance at music events should be unrelated to children’s rhythmic-perception scores.
Children’s polygenic scores should increase after a year of lessons, reflecting environmental enhancement of DNA.
Lesson attendance should predict improvement only among children with low rhythmic-perception scores.
If all children are automatically enrolled and transported to lessons, genotype differences in lesson exposure should shrink.
Explanation
This question assesses gene–environment correlation in behavioral genetics, where polygenic scores influence access to musical enrichment. Passive and active correlations occur when genes affect parental provision or child selection of environments. The vignette links higher scores to requested lessons and home enrichment. Choice D is correct, predicting reduced differences with automatic enrollment, disrupting correlation. Choice B distracts by implying environments change scores, reversing causality. Test by altering voluntariness in predictions. Strategy: identify correlation if genes predict environmental exposure.
Investigators examined epigenetic signatures of chronic loneliness. Adults completed a loneliness scale and were categorized as persistently high or persistently low loneliness across three assessments in one year. Blood samples were analyzed for methylation at regulatory regions near an immune-related gene, and inflammatory markers were measured. The high-loneliness group showed higher methylation at one regulatory region and higher inflammation; DNA sequencing showed no systematic differences between groups. The authors suggested that a social experience may be associated with altered gene expression regulation.
Which finding is most consistent with the vignette’s discussion of epigenetics?
Higher methylation implies the immune gene’s nucleotide sequence must differ between groups.
Loneliness causes individuals to inherit different immune alleles from their parents during adulthood.
Persistent loneliness is associated with differences in methylation near an immune gene without changes in DNA sequence.
Because loneliness is subjective, it cannot be associated with biological differences.
Explanation
This question explores gene–environment interaction through epigenetics in behavioral genetics, with loneliness altering immune methylation. Epigenetic changes regulate genes without sequence alteration, linked to social experiences. The vignette shows higher methylation and inflammation in loneliness, no sequence differences. Choice A aligns, highlighting methylation without change. Choice C assumes sequence differences. Verify regulation focus. Epigenetics connects social to biological.
A twin study examined how neighborhood resources interact with genetic liability for anxiety. Investigators recruited monozygotic (MZ) and dizygotic (DZ) twin pairs raised together until age 10, then some families moved (due to job relocation) to either a high-resource neighborhood (more parks, lower crime) or a low-resource neighborhood (fewer parks, higher crime). At age 16, anxiety symptoms were assessed. In low-resource neighborhoods, MZ twins were much more similar to each other in anxiety than DZ twins. In high-resource neighborhoods, MZ and DZ similarity was more comparable, and average anxiety was lower. Researchers argued the environment altered the extent to which genetic differences were expressed.
Based on the vignette, which conclusion about genetic predisposition and environment is supported?
Moving to a high-resource neighborhood changes twins’ DNA sequence, reducing heritability.
Greater MZ similarity in low-resource neighborhoods proves anxiety is caused only by genes.
High-resource neighborhoods appear to attenuate the expression of genetic liability for anxiety.
DZ twins should be as similar as MZ twins in all environments if anxiety is polygenic.
Explanation
This question assesses knowledge of gene–environment interaction in behavioral genetics, focusing on how neighborhood resources influence the heritability of anxiety. In twin studies, greater MZ than DZ similarity indicates genetic influence, but environmental factors can moderate this heritability, reducing genetic expression in protective settings. The vignette connects this by showing reduced MZ–DZ differences in high-resource neighborhoods, suggesting these environments attenuate genetic liability. Choice A is supported as it reflects how high-resource areas lower average anxiety and minimize genetic differences, consistent with moderated heritability. Choice B is a distractor because it misrepresents interaction as changing DNA sequence rather than expression, a common misconception in epigenetics. For similar questions, compare twin correlations across environments to gauge interaction effects. Always distinguish between heritability estimates and actual genetic changes when evaluating environmental moderation.
Researchers used a twin design to study how household chaos interacts with genetic influences on executive function. Monozygotic (MZ) and dizygotic (DZ) twins ages 9–10 completed the same inhibition task. Parents completed a household-chaos inventory (noise, unpredictable routines). In high-chaos homes, MZ twins were much more similar than DZ twins in inhibition performance. In low-chaos homes, MZ and DZ similarity was more comparable and average performance was higher. The authors suggested that calmer environments reduced the extent to which genetic differences accounted for variability.
Based on the vignette, which conclusion about genetic predisposition and environment is supported?
Because both twin types share a home, environment cannot influence executive function.
Low household chaos may attenuate genetic differences in inhibition performance.
High household chaos proves inhibition is entirely genetic because MZ twins are similar.
Low household chaos causes DZ twins to become genetically identical to MZ twins.
Explanation
This question assesses gene–environment interaction in behavioral genetics via twins, with chaos moderating inhibition heritability. Low chaos reduces genetic expression, equalizing twin similarities. The vignette shows comparable MZ–DZ in low-chaos homes. Choice C supports attenuation of differences. Choice B misclaims entirely genetic in chaos. Compare similarities across chaos levels. Interactions appear in varying heritabilities.
Investigators explored gene–environment correlation in children’s reading development. Children were genotyped for a polygenic score associated with higher verbal aptitude. Without informing teachers of genotypes, researchers observed that children with higher scores were more likely to join an after-school reading club and were also more likely to have parents who reported frequent library visits. The school offered the club to all students at no cost, and enrollment was voluntary. By the end of the year, club participation predicted higher reading comprehension, but the researchers noted that the same genetic factors linked to verbal aptitude may have increased children’s likelihood of selecting reading-rich environments.
What prediction is most consistent with gene–environment correlation as described?
Children’s polygenic scores should change after a year of reading club participation, indicating environmental causation.
Reading comprehension gains from the club should occur only in children with low verbal polygenic scores.
Children with higher verbal polygenic scores should be disproportionately represented in other language-enriching electives when available.
If the reading club is mandatory, children’s genotypes should become more similar across classrooms over time.
Explanation
This question evaluates comprehension of gene–environment correlation in behavioral genetics, where genetic factors influence environmental exposure, such as through active selection of enriching activities. Active gene–environment correlation involves individuals seeking environments that match their genetic predispositions, like high verbal aptitude leading to reading-rich choices. The vignette illustrates this with children having higher polygenic scores more likely to join voluntary reading clubs, correlating genes with environment. Choice B is correct as it predicts disproportionate representation in other electives, aligning with active correlation where genotypes drive selection. Choice C distracts by suggesting environments alter DNA, confusing correlation with causation and ignoring that polygenic scores are stable. In future questions, test for correlation by predicting reduced genotype–environment links under random assignment. A strategy is to differentiate active, passive, and evocative types based on how genes shape exposure.
Researchers investigated epigenetics in the context of early-life stress. Newborns were enrolled in a longitudinal study. Some infants experienced high caregiver instability during the first year (multiple primary caregivers due to housing transitions), while others had stable caregiving. At age 8, blood samples were analyzed for DNA methylation patterns near a glucocorticoid receptor gene involved in stress reactivity. Children exposed to early instability showed higher methylation at a regulatory region and, during a lab stress task, exhibited higher cortisol responses than children with stable caregiving. DNA sequencing showed no differences in the gene’s coding region between groups. The authors proposed that environmental experience altered gene expression potential without changing the DNA sequence.
Which finding is most consistent with the vignette’s discussion of gene–environment interaction?
Children with early instability show altered methylation near a stress-related gene despite identical DNA sequence in that region.
Children with early instability inherit new alleles for the glucocorticoid receptor gene from caregivers.
Methylation patterns are unrelated to environmental exposure and reflect only random measurement error.
Cortisol responses fully determine DNA sequence differences between groups by age 8.
Explanation
This question probes understanding of gene–environment interaction via epigenetics in behavioral genetics, where early stress alters gene expression without changing DNA sequence. Epigenetic modifications like DNA methylation can regulate gene activity, such as increasing stress reactivity through higher methylation near glucocorticoid receptors. The vignette links this to early caregiver instability, showing higher methylation and cortisol in affected children despite identical gene sequences. Choice A is consistent, emphasizing altered methylation without sequence changes, exemplifying epigenetic interaction. Choice B fails as it implies inheritance of new alleles, a misconception that confuses epigenetics with genetic mutation. For verification in similar items, confirm if outcomes involve expression changes rather than sequence alterations. Use this as a check: epigenetics explains environmental impacts on gene function without heritable mutations.