related to adaptive maternal effects are epigenetic effects. epigenetics is the study of long lasting changes in gene expression that are produced by modifications to chromatin instead of changes in dna sequence, as is seen in dna mutation. this "change" refers to dna methylation, histone acetylation, or the interaction of non-coding rnas with dna. dna methylation is the addition of methyl groups to the dna. when dna is methylated in mammals, the transcription of the gene at that location is turned down or turned off entirely. the induction of dna methylation is highly influenced by the maternal environment. some maternal environments can lead to a higher methylation of an offspring's dna, while others lower methylation.[22] the fact that methylation can be influenced by the maternal environment, makes it similar to adaptive maternal effects. further similarities are seen by the fact that methylation can often increase the fitness of the offspring. additionally, epigenetics can refer to histone modifications or non-coding rnas that create a sort of cellular memory. cellular memory refers to a cell's ability to pass nongenetic information to its daughter cell during replication. for example, after differentiation, a liver cell performs different functions than a brain cell; cellular memory allows these cells to "remember" what functions they are supposed to perform after replication. some of these epigenetic changes can be passed down to future generations, while others are reversible within a particular individual's lifetime. this can explain why individuals with identical dna can differ in their susceptibility to certain chronic diseases.