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 high concordance in identical twins and high heritability would be expected outcomes in twin studies examining such a trait. Some studies, such as 1, have shown that genetics play an important role in certain disorders, with estimates of heritability at around 80%, although this does not necessarily imply 100% concordance in monozygotic twins, as environmental factors can still influence the expression of a trait. Key points to consider in twin studies include:
- Monozygotic twin concordance rates
- Heritability estimates
- Influence of environmental factors on trait expression
- Genetic factors contributing to trait variation However, in the context of a trait determined almost entirely by genes, high monozygotic twin concordance and high heritability would be the expected result, as seen in certain genetic disorders with minimal environmental influence, according to recent studies like 1.
From the Research
Twin Study Results
The question asks about the expected result in a twin study for a trait that is determined almost entirely by genes, and very little by the environment.
- High monozygotic twin concordance is expected because the trait is largely determined by genes, and monozygotic twins share 100% of their genes.
- High heritability is also expected because the trait is determined almost entirely by genes.
Expected Outcome
Based on the above, the expected outcome in a twin study would be:
- High monozygotic twin concordance
- High heritability
Answer Choice
The answer choice that matches this expected outcome is:
- A. High monozygotic twin concordance and high heritability
Note
There are no research papers provided that directly assist in answering this question about twin studies and genetics 2, 3, 4, 5.