“…The corpus callosum is known to vary widely across individuals (Beaton, 2004) and is also known to be variable in response to environmental conditions (Castro-Caldas et al, 1999;Kopcik, Juraska, & Washburne, 1986;Schlaug, Jäncke, Huang, Staiger, & Steinmetz, 1995;Strauss & Wada, 1993). Its size is also known to be highly heritable (Scamvougeras, Kigar, Jones, Weinberger, & Witelson, 2003). Thus, in families we might expect to reduce variability between participants, better revealing differences in the morphology of the corpus callosum related to reading ability.…”