Muscle hypertrophy is the increase in the size of the transverse diameter of muscle fibers. Although the mechanisms and signaling pathways that regulate hypertrophy are known, it is still unclear how much genetics and epigenetics contribute to this process; whether both mechanisms participate jointly, or whether there is a more significant influence of one event than the other. Therefore, this study aimed to extensively review the literature and determine the role of genes and epigenetic mechanisms in regulating muscle hypertrophy associated with physical activity and sport. For this purpose, the Scopus and ScienceDirect databases were reviewed, and the PubMed and Google Scholar search engines were used, where 25 articles met the inclusion criteria. Results demonstrated that there are several regulatory genes of muscle hypertrophy, such as MSTN, PGC-1 α, STARS, and JunB, among others, as well as genetic polymorphisms and vital participation of DNA methylation, which together would control signaling pathways and gene networks necessary for the development of this process.