Following on the question of the relative roles of genes and environment during brain development is determining which specific genetic and environmental factors are most responsible. Multivariate analyses begin to open the way to asking whether the same factors are affecting different components of brain structure or function. For example, a principal components analysis of a cross-sectional sample within our data has shown that a single genetic factor appears to be responsible for 60% of the variance in cortical thickness, and that regions that are functionally and/or structurally connected also tend to be affected by similar genetic factors (Schmitt et al., 2008). A next step will be to determine if or how these factors change with age.
