Heredity gets attributed almost entirely to DNA, but researchers at the University of Geneva wanted to know whether changes to gene regulation could be passed down across generations even when the DNA sequence itself never changes. Working with the roundworm Caenorhabditis elegans, a study published in The EMBO Journal says the answer is yes — and that the effects can persist far longer than anyone might have expected.

The team temporarily disrupted the distribution of H3K27me3, a chemical modification to histone proteins that helps repress gene expression, by having the worms express a mutated form of a different histone, H3.3. That initial disruption reduced fertility sharply, from roughly 300 offspring per parent down to as few as 50 to 100. The worms’ descendants were genetically normal — nothing had changed in their DNA — yet the altered gene regulation and the fertility problems it caused persisted for at least 15 generations.

Digging into how that persistence worked, the researchers identified two distinct mechanisms operating in sequence: one that establishes the new, altered epigenetic state immediately after the initial disruption, and a separate one that maintains that state across the generations that follow. Lead researchers Özdemir and Stubbe described the durability of the effect as unexpected: they found that the effects did not disappear once the initial trigger was removed, noting that maintaining an altered epigenetic state appears to depend on a sequence of specialized mechanisms rather than any single process.

Professor Florian Steiner, who oversaw the work, sees broader implications in the finding. A temporary disruption of gene regulation, he said, can leave a lasting and transmissible mark on an organism’s descendants — and that kind of inheritance, distinct from anything encoded in DNA itself, could represent an additional way organisms respond and potentially adapt to changing environmental conditions.

Journal: The EMBO Journal
Article Title: Transgenerational inheritance of altered H3K27me3 in wild-type Caenorhabditis elegans
DOI: 10.1038/s44318-026-00907-9
Publication Date: September 18, 2026

Source: EurekAlert