There have now been several studies exploring heritability of different aspects of brain structure (Baare et al., 2001; Posthuma et al., 2000; Tramo et al., 1998; Wright, Sham, Murray, Weinberger, & Bullmore, 2002). Results in adult populations have consistently shown that variation in most brain volumes is highly driven by genetic factors. Topological features such as gyrification have been less studied, but available reports indicate that cortical folding has strong environmental influences (White, Andreasen, & Nopoulos, 2002). A study of cortical gray matter density in 10 MZ and 10 DZ adult twin pairs found regional variation in heritability, with highest values in frontal and temporal areas (Thompson, Cannon, et al., 2001). An interesting MRI study of brain volumes in an extended kinship of baboons also found similar areas to be the most heritable (Rogers et al., 2007).
