From the Guidelines
The correct answer is A. High monozygotic twin concordance and high heritability. When a trait is determined almost entirely by genes with minimal environmental influence, monozygotic (identical) twins, who share 100% of their genetic material, would show high concordance for that trait, meaning both twins would typically express the trait similarly. Additionally, such a trait would demonstrate high heritability, which is a statistical measure of how much of the variation in a trait within a population can be attributed to genetic factors. Heritability is high when genetic factors strongly influence trait expression relative to environmental factors. Since the question specifies that the trait is determined "almost entirely by genes, and very little by the environment," both the concordance rate in identical twins and the heritability estimate would be high, making option A the correct answer. Some studies, such as 1, have shown that schizophrenia has a high heritability estimate of around 80%, indicating a strong genetic component, although the concordance rate for monozygotic twins is around 40-50%, which is not as high as might be expected for a trait entirely determined by genes. However, this question is about a hypothetical trait that is determined almost entirely by genes, so the principles of high monozygotic twin concordance and high heritability apply. Key points to consider include:
- High heritability indicates a strong genetic influence on a trait
- Monozygotic twin concordance is a measure of how often both twins express the same trait
- Traits with high genetic influence and low environmental influence are expected to have high heritability and high monozygotic twin concordance.
From the Research
Twin Study Results
- A trait that is determined almost entirely by genes, and very little by the environment, is expected to have high monozygotic twin concordance and high heritability 2.
- High monozygotic twin concordance indicates that the trait is highly influenced by genetics, while high heritability suggests that the trait is largely determined by genetic factors rather than environmental factors.
- The study by 2 found that estimates of heritability cluster strongly within functional domains, and across all traits, the reported heritability is 49%, suggesting that genetics play a significant role in determining many traits.
Heritability and Environment
- The study by 3 found that intelligence is a trait with unusual properties that create a large reservoir of hidden gene-environment networks, allowing for the contribution of high genetic and environmental influences on individual differences in IQ.
- However, this study does not directly address the question of twin concordance and heritability, but rather highlights the complex interplay between genetic and environmental factors in determining traits like intelligence.
Conclusion Not Applicable
As per the given instructions, a conclusion section should not be provided.
Relevant Findings
- The correct answer is A. High monozygotic twin concordance and high heritability, as this is the expected result for a trait that is determined almost entirely by genes, and very little by the environment 2.
- The other options (B, C, D, E) are incorrect because they do not accurately reflect the expected results for a trait with high genetic influence and low environmental influence.