Figure 5.
Proportions of variance in white matter integrity in different lobes of the brain (average lobar values of FA) due to genetic (a2), shared environment (c2) and unique environment (e2) components, under the full (a) and the best-fitting model (b). For each lobe, the average FA in white matter (defined as FA >0.3) served as the observed variable for the ACE structural equation models. *p(A) = 0.04; **p(A) = 0.006, #p(A) < 0.001; ##p(A) < 0.001; §p(A) = 0.003. p(A) in other lobes and p(C) are not significant. These data show the dominant effect of genes on white matter integrity and provide little evidence to support a strong environmental effect (that is independent of genetic variation). L, Left; R, right.