a particular phenotype in MZ and DZ twins to estimate the heritability of a trait(Plomin et al. 1994), whereas multivariate studies can analyze the links between genetic and environmental effects on specific regions of interest in the brain. Contributions of additive genetic (A), common or shared environmental (C), and unique environmental (E) effects on variations of a phenotype can be modeled using structural equation modeling (SEM). SEM allows for parameter estimations, while the Falconer method uses correlation analysis to test whether genetic or environmental factors contribute significantly to individual differences (parameter calculation). SEM can also be used to determine whether the traits defined by neuroimaging are heritable, and how heritability can explain brain development.
