Read the article and answer the following questions in a 250 word essay.

Question

Why are twin studies valuable in behavioral genetics research?

What does the research say about the effect of environment on IQ scores in poor homes versus affluent homes? What does this suggest?

What is the conclusion of the article? How might these findings be useful to other researchers?

Heritability: its all relative

Heritability is one of the foundational concepts of behavioral genetics, but its meaning is not always clear. Does a study showing that IQ is highly heritable among affluent children in Denmark have any implications for poor children in the United States? Or is it largely irrelevant?
New research is making it increasingly obvious that the answer is: "It depends." Heritability, as the term is used by behavioral geneticists, is a statistical measure defined in relation to a particular environment and a particular population. The only way to find out whether the heritability of a trait is the same for other environments and populations is to go out and study them.
In a recent study, University of Virginia psychologist Eric Turkheimer, PhD, and his colleagues did just that. Their study explored the heritability of children's IQ in different populations within the United States--those with high socioeconomic status (SES) and those with low SES.
Previous studies of children's IQ have produced conflicting results. On the one hand, some studies of twins and adoptees have found large genetic effects. On the other hand, studies of impoverished children adopted by well-to-do families suggest that the environment plays an important role.
For their study, published last year in Psychological Science (Vol. 14, No. 6), Turkheimer and his colleagues analyzed data from several hundred monozygotic and dizygotic twins included in the National Collaborative Perinatal Project, which followed more than 48,000 mothers and their children from birth to age 7.
Turkheimer and his colleagues found that, among poor families, children who grew up in the same household tended to have similar IQ scores, regardless of how genetically similar they were. Around 60 percent of the variance was accounted for by environment, while genes contributed almost nothing. Among affluent families, the reverse was true. Monozygotic twins with identical genes tended to have much more similar IQ scores than dizygotic twins, regardless of family environment.
The findings suggest that it makes little sense to speak in general about the heritability of a trait such as IQ. For large populations of people who live in diverse environments, such as children in the United States, such broad statements may be meaningless. The environment can make genes extremely important in some subpopulations, but insignificant in others, notes Turkheimer.
Such findings do not challenge the traditional definition of heritability--the proportion of variance on a particular trait that is accounted for by genetic factors within the population as a whole, says Terrie Moffitt, PhD, of the University of Wisconsin and King's College London. But they are important reminders that heritability can vary dramatically depending on the population and the environment that is being studied.

Answer 1

Twin studies are invaluable in behavioral genetics research because they allow scientists to disentangle the influence of genetics and environment on various traits, particularly intelligence. By examining monozygotic (identical) twins, who share nearly 100% of their genes, and dizygotic (fraternal) twins, who share about 50% of their genetic material, researchers can measure the heritability of traits like IQ under different environmental circumstances. This comparative approach helps illuminate whether observed differences in IQ can be attributed more to genetic similarities or to differing environments.

Recent research, notably by Eric Turkheimer and his colleagues, shed light on how environmental context influences IQ scores among children from differing socioeconomic backgrounds. The findings revealed that within low socioeconomic status (SES) families, environmental factors accounted for about 60% of the variance in IQ, rendering genes less impactful. In contrast, in affluent families, genetics played a more significant role, as monozygotic twins had similar IQ scores regardless of environmental influences. This suggests that while genetic factors are crucial in resource-rich environments, environmental variables play a dominant role in impoverished settings, highlighting the importance of context in understanding heritability.

The conclusion of the article emphasizes that heritability should not be viewed as a fixed measure, as its significance fluctuates across different populations and environments. These findings are crucial for researchers as they indicate the need for tailored approaches in studying heritability, particularly when considering interventions aimed at improving intelligence and educational outcomes in diverse socio-economic contexts. This nuanced understanding can guide policy decisions and inform educational strategies aimed at helping children from disadvantaged backgrounds.