1. Given the following concordance rates, is the identified trait primarily genetic or environmental? Explain.
MZ Twins DZ Twins
Height 0.94 0.44
Measles 0.95 0.87
Migraine headaches 0.80 0.39
Body fat percentage 0.73 0.22
They are both, but MZ twins have identical genetics, you would expect their correlations to be higher. Lower correlations suggest environmental.
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To determine whether a trait is primarily genetic or environmental, we can analyze concordance rates among monozygotic (MZ) twins and dizygotic (DZ) twins. MZ twins are genetically identical, while DZ twins share approximately 50% of their genetic material, similar to non-twin siblings.
Concordance rates indicate the likelihood of both twins sharing a particular trait. If the trait has a higher concordance rate among MZ twins compared to DZ twins, it suggests a stronger genetic influence. On the other hand, if MZ and DZ twins have similar concordance rates, it is more likely influenced by environmental factors.
Looking at the concordance rates provided:
1. Height: The concordance rate for MZ twins is 0.94, whereas for DZ twins, it is 0.44. The fact that MZ twins have a significantly higher concordance rate suggests that height is primarily influenced by genetics.
2. Measles: MZ twins have a concordance rate of 0.95, while DZ twins have a concordance rate of 0.87. Although the concordance rate is high for both types of twins, the slight difference suggests that genetics plays a slightly stronger role than environmental factors.
3. Migraine headaches: MZ twins have a concordance rate of 0.80, while DZ twins have a concordance rate of 0.39. Again, the significantly higher concordance rate among MZ twins points to a strong genetic component in the development of migraines.
4. Body fat percentage: The concordance rate for MZ twins is 0.73, compared to 0.22 for DZ twins. The substantial difference between the two rates implies that body fat percentage is predominantly influenced by genetic factors.
Based on these concordance rates, we can conclude that the identified traits of height, measles vulnerability, migraine headaches, and body fat percentage have a primary genetic influence. However, it's worth noting that while genetics play a strong role, environmental factors can still contribute to variations within the trait.