However, from an evolutionary perspective, Matosin et al. [3] hypothesize that the persistence of the FKBP5 risk haplotype in the population is associated with increased anxiety consequent to stressful life events promoting survival behaviors; jointly, some clinical phenotypes associated with FKBP5 variants may not have reduced fertility, since the psychopathology associated with risk alleles occurs in adverse environmental conditions but not in favorable ones; i.e., from the gene–environment interaction approach, it would correspond to a model of differential sensitivity [43]. The gene discussed is FKBP5; the disease is Anxiety.