Inter- and transgenerational inheritance of behavioral phenotypes

Adult animal behaviors are determined by complex and dynamic changes in gene expression in different brain regions and are influenced by life experiences and environmental exposures. These stimuli affect gene expression through intricate mechanisms of regulation that largely implicate epigenetic factors, such as, DNA methylation, histone post-translational modifications, and non-coding RNAs (ncRNAs). Through these molecular pathways, some of the behavioral phenotypes associated with life experiences can be stably transmitted to descendants, sometimes across several generations. Rodent studies indicate that parental stressful and traumatic experiences can lead to behavioral despair, risk-taking behaviors, altered sociability and atypical responses to stressful stimuli in the offspring, whereas parental environmental enrichment has been associated with improved cognition and stress resilience in the offspring. Similar observations have been made in humans; children and grandchildren of genocide survivors show increased psychopathology and emotional disturbances. At the molecular level, changes in germline ncRNAs have been identified as likely vectors of transmission in rodents. The mechanisms linking behavioral stimuli to the germline, and factors responsible for these changes and their persistence across generations remain, however, largely unidentified.