In humans, variation within the serotonin transporter gene (SLC6A4) that results in reduced gene expression has been linked to a high trait anxiety phenotype (Lesch et al., 1996; Canli and Lesch, 2007; Caspi et al., 2010) and marked changes in the activity of emotion circuits in the brain (Brown and Hariri, 2006; Murphy et al., 2013); although meta‐analyses have called into question the gene‐behavior association (Munafò et al., 2009; Risch et al., 2009). Here, SLC6A4 is linked to Anxiety.