Given the impact of the “epigenetic” mechanisms that encode environmental information from both internal and external bodily sources, a single genotype–phenotype linkage cannot be established without simultaneously considering the multifaceted effects of the 5-HTT gene, which has been found to be associated with anxiety, morality, and even culture structures (Fergusson et al., 2011; Mrazek et al., 2013; Perkins et al., 2013; Yang et al., 2019). Here, SLC6A4 is linked to Anxiety.