Describe how scientists use behavioral genetics to study heritability.

•   Behavioral genetic designs look at both genetic and environmental influences and allow us to estimate the heritability of traits and diseases. By heritability, we mean the extent to which genes contribute to differences in a trait among individuals.
•   Heritability is expressed as a percentage and indicates how much of the variability in a trait across individuals is due to genes.
•   Student may include the three major misconceptions: Heritability applies to a single individual rather than differences among individuals—in fact, it applies only to groups; Heritability tells us whether a trait can be changed—in fact, highly heritable traits can be malleable; Heritability is a fixed number—in fact, in can differ across time periods and populations.
•   Scientists estimate heritability by means of one of three behavioral genetic designs: family studies, twin studies, and adoption studies. In such studies, scientists note the presence or absence of a behavioral trait or a psychological disorder among different relatives. These studies determine how much genetics contributes to the expression of that trait or disorder.