1 Circles represent latent additive genetic (A), shared environmental (C) and non-shared environmental (E) factors. a1, a2, e1, e2, c2 represent genetic and environmental path estimates. rg and re represent genetic and environmental correlations between ADHD and VLF activity, Parameters for ADHD (heritability and unique environmental estimates) are fixed values according to meta-analysis (Faraone, et al., 2005).