Final answer:
Heritability on the scale of liability pertains to the estimation of genetic variance based on underlying risk factors, whereas heritability on the scale of observation is based on actual observed trait variations. High heritability indicates that genetics significantly influence trait expression, as was exemplified by the Minnesota Study of Twins Reared Apart.
Step-by-step explanation:
The difference between heritability on the scale of liability versus the scale of observation involves understanding how genetic variance is estimated based on different types of data. Heritability on the scale of liability considers underlying risk factors that cannot be directly observed but contribute to the variation of a trait, while heritability on the scale of observation is calculated based on actual observed variations in a population. When discussing heritability, scientists are referring to the proportion of phenotypic variation in a population that is due to genetic differences among individuals. A higher heritability indicates that genetic factors play a substantial role in the expression of that trait. The Minnesota Study of Twins Reared Apart highlights the heritability of certain personality traits, demonstrating that even when separated at birth, identical twins showcased remarkably similar personality characteristics. This implies a strong genetic component to these traits.