Sperm cells carry past trauma in their epigenetics

Generational wounds may live in our genes. New research suggests that childhood trauma leads to a difference in the epigenetics of a sperm cell, which can impact a child's development and also be passed on by that child via epigenetic inheritance. According to the new study, a parent's particular experiences and behaviors may have a larger effect on future generations than previously assumed.

The past is present

The study, published in the journal Molecular Psychiatry, specifically looked at the epigenetics of sperm cells from people who were exposed to high levels of stress in their childhood. "Understanding inheritance through genes and DNA has been one of the most crucial elements of our understanding of biology," Dr. Jetro Tuulari, an associate professor in the Department of Clinical Medicine at the University of Turku in Finland and the author of the study, said to Live Science. "We are now doing research that questions whether or not we have a complete picture."

Epigenetics is the study of how cells control gene activity without changing the DNA sequence, but instead altering "which genes can be switched on," said Live Science. Researchers here looked at two epigenetic markers: DNA methylation and small noncoding RNA. The findings showed a "different epigenetic profile compared with the sperm from men who reported less trauma," with the pattern holding "even after the researchers checked if the differences could be attributed to other factors, such as drinking or smoking behaviors." These results "provide further evidence that early life stress influences the paternal germline epigenome and supports a possible effect in modulating the development of the central nervous system of the next generation," the study said.

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Generation after generation

While the study found epigenetic changes in the sperm cells of those who experienced distress as children, "the inheritance of these findings has not yet been proven, so further research is needed," University of Turku Professor Emeritus Hasse Karlsson, who worked on the study, said in a press release. "Next, we want to study childhood maltreatment, epigenome of sperm, and offspring characteristics together," added Tuulari in the press release. "Demonstrating epigenetic inheritance in humans would rewrite the rules of inheritance, which highlights the need for further research."

Scientists have long been interested in how the behavior and experiences of parents genetically affect their children, especially when it comes to the sperm cell. "There must be a huge component of the pathogenesis which is not simply explained by genetic predisposition," Raffaele Teperino, a physiologist and pharmacologist at Helmholtz Munich, said to The Scientist. For example, a 2024 study found that paternal diet and weight can affect their offspring's metabolic health — even if the offspring has a healthy diet.