The inheritance of genetic information has long been established and it is now apparent that epigenetic information can also be transmitted from one generation to the next. This phenomenon, where gene expression patterns are inherited with no change to the DNA sequence, is referred to as transgenerational epigenetic inheritance (TEI). It has been observed in a range of species, including Mus musculus, Drosophila melanogaster, and Caenorhabditis elegans and has implications for natural selection, viral defence, and germline immortality. The research presented here utilizes C. elegans in an RNA interference (RNAi) assay to assess the inheritance of gene silencing. Parent animals are subjected to an RNAi trigger to silence a germline gfp transgene and following generations are assessed for gfp expression in the absence of this trigger. Previous work has distinguished three distinct parts to this transgenerational silencing process, including initiation of gene silencing, the establishment of silencing inheritance within the parental germline, and the maintenance of this silencing signal within the progeny. This study examines the highly homologous predicted histone methyltransferases set‑9 and set‑26 as well as a third similar gene termed Y73B3A.1 to determine in which stage of TEI they are involved. The results of the study implicate all three as having roles in the establishment of a heritable silencing signal and set‑26 also acting to maintain this signal through multiple generations. Genome comparisons with related nematode species suggests that set-9 is a duplication of set-26. Further research was conducted to determine whether these genes were required within the parental generation to transmit a heritable silencing signal or within the first generation of progeny to receive such a signal. Our results suggest that both set‑9 and Y73B3A.1 are required within the parent animals in order to properly establish a heritable silencing signal.