Such methods may have to reflect a somewhat different conceptual model as well. Two things are typically absent in GWA studies: the environment and development. The development of ocular dominance columns and normal vision depends critically on the experience of patterned light (Wiesel & Hubel, 1965). Although it would of course be extremely unlikely for an infant not to have this form of experience, it is nevertheless necessary. It is a truism that genes are expressed in particular environments over the course of development, yet this is not reflected in the GWAS design. Progress in understanding the genetic influences on complex traits may require analytic approaches that account for this interplay.
