**4. Transgenerational effect of the social stress and environment**

The continuous epigenetic effects of environmental events were presented in the previous sections. In influencing behavioral and neurobiological effects, these consequences seem to play a crucial role. However, it may also be the case that these ecoinduced influences are capable of persisting over centuries. One mechanism by which this transmission occurs [64] may be transgenerational continuity in maternal behavior. There is evidence in rodents that coercive caregiving as well as variance in maternal LG can change the enhancement of female offspring so that each offspring as well as grand offspring can also find these maternal characteristics. In the medial preoptic position of the hypothalamus of female offspring, maternal LG tends to alter the DNA methylation as well as the Esr1 phrase [65]. Throughout the postnatal period, during which adulthood continues, these implications emerge. ER-alpha quantities possess a crucial part in deciding the responsiveness of females to circulating oestrogens for late gestation, and stated specific responsiveness predicts the quality as well as the number of interactions between postnatal mother babies. Individual differences in maternal LG are actually transferred from mother to offspring (generation F1) as well as to grand offspring (generation F2) as a result of the epigenetic changes [64, 66].

In studies of child violence, variance of behavioral segmentations is found across species. In rats, both the variation of DNA methylation and the BDNF phrase in the prefrontal cortex can be correlated with the transgenerational continuity of violence. Females' BDNF term tends to be decreased if experienced violence in childhood and methylation of BDNF IV promoter DNA in the prefrontal cortex is to be improved by this situation as well. The offspring of these females likewise have increased Bdnf IV promoter DNA methylation in the prefrontal cortex. Addition to these, offspring of stated females is likely to have enhanced methylation of BDNF IV promoter DNA in the prefrontal cortex [67]. Surprisingly, scientific studies on cross-fostering recommend that prenatal elements may be linked to the transmission of violence and also the epigenetic variance related to this specific phenotype rather than postnatal events with the dam. In fact, the direct inheritance of epigenetic change is another path by which perinatal epigenetic, as well as behavioral effects, may persist over generations. Although it has long been believed that during the first stages of embryogenesis, a complete erasure of epigenetic disruption to the genome is at hand. Revelation of imprinted genes (genes that are expressed depending on the parent from whom they are inherited) has led to widely believed speculation that the previous generation's epigenetic "memory" is actually retained and transmitted to the genome [68].

The epigenetic inheritance of the toxicological exposure effect has been studied and also suggests the existence of the patriline effects for many decades [69]. More recently, in offspring exposed to separation (F1), the offspring of separated males (F2), and the grand offspring of separated males (F3), the transgenerational impact of maternal separation have been investigated. With this paradigm, during the postnatal era, mice were exposed to unforeseen separation from the dam. Depressivelike behaviors that were activated in the offspring of the F1 model were found to be contained in both F2 and F3 generation mice [70]. DNA methylation patterns caused by separation have been shown to be contained in the sperm and brains of F1 male mice and also in the brains of F2 males. Hypermethylation of the Mecp2 gene as well as hypomethylation of the Crfr2 gene resulted in these epigenetic consequences. As a result, it appears that the epigenetic variation that is created with the early life environment's aspect could be encoded within the germ cells, leaving traces of stress and social environment on the next descendants through transgenerational approach.
