About one in five adults in Europe and the United States grew up with some form of childhood maltreatment and for men, a small but growing body of research suggests that experience may have left a molecular trace in their sperm that wasn’t there before.
Men who were abused or neglected as children show differences in the epigenetic makeup of their sperm as adults. Dozens of small RNA molecules appear at different levels. Three regions of the sperm genome carry different patterns of chemical modification. Some of those regions sit near genes involved in brain development, which is the part that makes this more than just a curiosity.
The question underneath all of this is whether what happens to a father in childhood could leave a molecular imprint on his sperm not through how he parents, but through actual biological information carried in the cell. Animal studies have been pointing in this direction for years. Stress the father, alter the sperm, and the offspring show changes in behavior and brain development. But mice aren’t people, and the human data has been thin. This paper adds to a pile of exactly three prior human studies on the same question, which tells you something about how early this field still is.
The researchers pulled from a Finnish birth cohort that recruited thousands of families starting around 2011. Fathers had already filled out a childhood maltreatment questionnaire โ covering physical and emotional abuse, sexual abuse, physical and emotional neglect, everything through age 18 โ when their partners were pregnant. About a decade later those men came back, gave sperm samples, and got divided into two groups based on those old questionnaire scores. The lab staff doing the genomic analysis didn’t know who was in which group. They ran two kinds of tests: one looking at small RNA molecules in the sperm, the other at DNA methylation, which is a chemical tag on the genome that influences whether genes switch on or off. Both analyses compared high-maltreatment men to low-maltreatment men, adjusting for age, BMI, smoking, drinking, and current mental health.
The RNA analysis had 14 men on the high end and 16 on the low, which is a small number, and found 68 RNA molecules that differed significantly between groups. One of them โ a microRNA called miR-34c-5p โ had already been flagged by a previous independent study as lower in men with more adverse childhood experiences. Finding it again, in a different country with a different questionnaire, is the most credible result in the paper, because that’s what replication looks like and it’s rare enough in this literature to be worth noting. The DNA methylation analysis, with 25 and 30 men per group, turned up three genomic regions that differed, near genes called CRTC1, GBX2, and WFIKKN1. The first two connect to brain development and mood regulation. The third is mainly a muscle thing, which the authors don’t try to explain away.
None of this shows that fathers transmit trauma to their children through sperm. The researchers know that, and say so, using words like “speculate” and “possible effect” throughout. Finding that sperm looks epigenetically different is not the same as showing those differences do anything after fertilization, and that gap from sperm epigenome to a child’s brain โ is enormous and completely unaddressed here. The study is cross-sectional, meaning one sperm sample per man, so nobody knows whether these patterns are stable marks laid down in childhood or just a snapshot of something more fluid. The maltreatment data is retrospective self-report, collected years before the sperm samples, and can’t reach back to the earliest years of life when some of the worst things happen. Sample sizes throughout are small enough that the whole thing needs replication before anyone should feel confident in it.
What survives all that is genuinely interesting, though. The miR-34c-5p finding is now showing up across multiple independent samples. The methylation differences near brain-development genes are plausible enough to warrant follow-up. And the tRNA-derived small RNAs the study identifies are newer territory entirely, something to watch rather than something to conclude from. The paper is careful in a field that often isn’t, and it’s asking a real question โ whether the body keeps a record of childhood harm in the germline, in a form that could matter for the next generation. That question doesn’t have an answer yet. This study is evidence that it’s worth asking.
Reference:
Jetro J. Tuulari, Matthieu Bourgery, Jo Iversen, Thomas Gade Koefoed, Annukka Ahonen, Ammar Ahmedani, Eeva-Leena Kataja, Linnea Karlsson, Romain Barrรจs, Hasse Karlsson, and Noora Kotaja. “Exposure to childhood maltreatment is associated with specific epigenetic patterns in sperm.” Molecular Psychiatry, vol. 30, pp. 2635โ2644 (2025). https://doi.org/10.1038/s41380-024-02872-3
