This thesis aims to examine critically philosophical debate that has been based on the findings of epigenetics. Epigenetics is characterized by the fact that expression itself and expression levels of genes are regulated through factors determined by the nutritional status and mental experience of individuals. This implies that people can control their gene expression by choosing their own environment and giving them the intended mental experience, which is presented as the main basis for establishing free will. The free will argument associated with epigenetics has been presented as a major basis for overcoming genetic determinism or materialistic mechanics in the fields of evolution, genetic engineering, and neuroscience, and furthermore, to treat various diseases caused by gene mutations. It implies the possibility of controlling each person's behavior as desired, so much attention has been focused on philosophical implication. However, the cases in which the epigenetic basis is revealed scientifically are only a few. This will not be easy to improve even if research continues to be done in the future. It is not easy to find a universal epigenetic rule that regulates DNA expression sites, as human organisms are complex organisms that are difficult to be reduced to basic structures, as has been fully demonstrated in the discussion of past genetic engineering stability issues. It is highly appreciated that epigenetics can explain both a mechanism beyond the controversy of past nature and nurturing, and provide grounds for overcoming genetic determinism. However, if the generic principle for controlling the gene expression site is difficult to establish, suggesting epigenetic genetics as a basis for establishing free will will not only be logically contradictory but may also lead to various social problems. Therefore we need to take a more cautious approach in this regard.