Final answer:
The heritability ratio is used to measure the proportion of variability in people's emotional dispositions that can be accounted for by genes.
Step-by-step explanation:
Behavioral genetics studies suggest that the proportion of variability in people's emotional dispositions that can be accounted for by genes is the heritability ratio. Heritability refers to the fraction of difference among people's emotional dispositions that is attributed to genetics. For example, the Minnesota Study of Twins Reared Apart found that some emotional traits have a heritability ratio of more than 0.50, indicating that a significant proportion of the variability in those traits can be attributed to genetic differences among individuals.