SLC6A4 and psychiatric disorder: Although some studies could not confirm an interaction effect of SERT genotype and early life adversities (see review: Houwing et al., 2017), other studies have shown a significant influence of the SERT+/– genotype on behaviors putatively related to psychiatric disorders (Olivier et al., 2008; Bartolomucci et al., 2010; van der Doelen et al., 2013; Houwing et al., 2019).