limited. Although it is now recognized that linkage studies were underpowered to detect genes of small effect, such as those now thought to be operating in psychiatric conditions, this atheoretical approach was retained in the next generation of gene-finding methods that replaced linkage—the implementation of genome-wide association studies (GWAS) (Cardon 2006). GWAS also have the general framework of scanning markers located across the entire genome in an effort to detect association between genetic markers and disease status; however, in GWAS over a million markers (or more, on the newest genetic platforms) are analyzed. The next technique on the horizon is sequencing, in which entire stretches of DNA are sequenced to know the exact base pair sequence for a given region (McKenna et al. 2010). From linkage to sequencing, common across all these techniques is an atheoretical framework for finding genes that necessarily involves conducting very large numbers of tests. Accordingly, there has been great emphasis in the field of genetics on correction for multiple testing (van den Oord 2007). In addition, the estimated magnitude of effect size of genetic variants thought to influence complex behavioral outcomes has been continually shifted downward as studies that were sufficiently powered to detect effect
