Post-traumatic stress disorder (PTSD) is something we are now accustomed to attributing to the effects of war. We used to call it “shell shock.” Today we know that trauma is not only experienced individually, but shared through generations as well. Researchers have known for awhile that trauma experienced by mothers during pregnancy can affect children and even alter the way DNA is expressed without changing its sequencing. A recent study shows that it can also alter microRNA in the sperm of mice, causing anxiety and depression in offspring. The experiences of your parents and grandparents may influence the person you are today.
Source: Dr. Megan McElheran, and Annie Murphy Paul, “Trauma: Our Genetic Inheritance,” filmed July 2011, TED video, 16:40 and 16:31, https://archive.tedx.amsterdam/2014/08/trauma-can-inherited/