There are two major directions of genetic investigation of complex phenotypes such as psychophysiological traits. The first line of research involves elucidation of genetic architecture of the phenotypes using the assessment of heritability and genetic correlations among different variables using biometrical genetic analysis of twin and family data. The second direction of research focuses on the identification of specific genes contributing to overall heritability using linkage and association studies. There are excellent reviews and primers on the genetic analyses of twin data (Boomsma et al., 2002; Evans et al., 2002; Posthuma et al., 2003; Rijsdijk and Sham, 2002; van Dongen et al., 2012) and genetic association analysis (Hardy and Singleton, 2009; Hirschhorn and Daly, 2005; Wang et al., 2005; Yang et al., 2013). A reader interested in these methodologies is advised to consult with these sources. A brief overview of these methods is provided below.
