A research team examines concordance rates for a mood disorder across 800 monozygotic and 800 dizygotic twin pairs raised together. They report concordance of 0.55 for monozygotic pairs and 0.22 for dizygotic pairs. The investigators apply behavioral genetic models to estimate heritability while acknowledging shared environment as a covariate.
Why is the assumption that twins share their environment equally important to interpret cautiously?
- Acheck_circle
Monozygotic twins may be treated more similarly than dizygotic twins, inflating heritability estimates
- B
Dizygotic twins always share more environment than monozygotic twins
- C
Heritability estimates apply to single individuals
- D
Concordance rates are unaffected by environment
Explanation
The equal-environments assumption is contested because identical twins may elicit more similar treatment, which can bias heritability estimates upward.