The stage for this balancing act is spermatogenesis, the process by which spermatozoa are produced through the differentiation of spermatogonial stem cells, or SSCs, and their subsequent spermatogenic descendants. In the male gonads of mice, the model organism at the heart of most of this research, epigenetic regulation is central to controlling this process. Epigenetic regulation, broadly defined, refers to the layer of chemical tags and chromatin structures that governs which parts of the genome are active without altering the underlying DNA sequence. As male germ cells progress through spermatogenesis, their transcriptional activity changes dynamically to enable the transition from mitotically dividing SSCs to meiotic spermatocytes, and then through the profound morphological changes necessary to generate spermatozoa. Each of these steps demands a wholesale reconfiguration of the epigenetic landscape.

The review emphasizes that an ensemble of fine-tuned epigenetic factors and mechanisms regulates this transcriptional activity. These include DNA methylation, the addition of methyl groups to cytosine bases; a rich vocabulary of histone modifications, such as the methylation and acetylation marks on histone H3 that the authors catalog by residue and modification type, including H3K4me1/2/3, H3K27ac, H3K27me3 and H3K9me2; and the action of architectural proteins such as CTCF and its germline-specific relative BORIS, which organize the genome into three-dimensional domains known as topologically associated domains. Enzyme families including DNA methyltransferases, histone acetyltransferases, histone deacetylases, histone methyltransferases and lysine demethylases write and erase these marks, while polycomb repressive complexes 1 and 2 help lock down inappropriate gene expression. Modern mapping technologies, from chromatin immunoprecipitation followed by sequencing to ATAC assays for accessible chromatin, CUT&RUN, CUT&Tag and chromosome conformation capture methods, have made it possible to chart these features at ever finer resolution.

The first act of the drama concerns the SSCs themselves. These stem cells must maintain their own population through self-renewal while also committing to differentiation, and the review describes how epigenetic plasticity underpins this choice. Regulatory factors such as the promyelocytic leukemia zinc finger, PLZF, are associated with the stem cell state, and the chromatin of undifferentiated spermatogonia remains comparatively open and responsive, allowing these cells to respond to cues that tip them toward either maintenance or differentiation. As differentiating spermatogonia emerge, the epigenome begins to shift, priming the cells for the sweeping changes ahead. This plasticity is not a flaw but a feature: without it, the germline could not replenish itself across the reproductive lifespan of the animal.

The second act is the mitosis-to-meiosis transition, arguably the most dramatic reprogramming event in the entire process. Cells that have been faithfully copying themselves through mitosis must now halve their genetic content, and their transcriptional program must change accordingly to support entry into meiosis as spermatocytes. The review describes how epigenetic mechanisms coordinate this switch, with changes in DNA methylation patterns, histone marks and chromatin accessibility working in concert to silence mitotic programs and activate the meiotic machinery. Super-enhancers, clusters of regulatory elements that drive high-level expression of key identity genes, are part of this coordination, as are changes in the three-dimensional folding of the genome that bring distant regulatory elements into contact with their target genes.

The third act is post-meiotic maturation, and it is here that the tension between flexibility and stability becomes most visible. Round spermatids must transform into elongated spermatozoa, a process that involves replacing the majority of histones with protamines, the small, highly basic proteins that allow DNA to be packed with extraordinary density into the head of the sperm. Transition proteins bridge this exchange. This near-total repackaging means that most histone-based regulatory information is dismantled, yet the review highlights that some epigenetic marks are stably maintained in spermatozoa. DNA methylation, in particular, must be preserved through this upheaval, and a subset of retained histones and their modifications may carry information forward as well.

That preserved information matters beyond the sperm itself. The review describes how some epigenetic marks maintained in spermatozoa can, in some cases, be passed to the embryo and influence offspring phenotypes. This possibility, which connects germline epigenetics to the broader and often debated field of intergenerational inheritance, gives the stability side of the double-edged sword its full weight. Marks that survive the protamine exchange and the early embryonic reprogramming that follows fertilization represent a channel through which the paternal germline can, in principle, shape the development of the next generation. The Mansuy laboratory has a long history of work on how environmental experience can leave traces in the germline, and this review situates the molecular machinery of the postnatal male germline within that larger question.

The sword cuts both ways, however, and the review is explicit about the consequences of disruption. When the fine-tuned ensemble of epigenetic factors goes awry, the result can be sub- or infertility. Spermatogenesis is a long, staged process with many checkpoints, and errors in DNA methylation establishment or maintenance, misregulated histone modification, or faulty chromatin remodeling at any stage can compromise the production or quality of spermatozoa. The germline’s need for plasticity makes it inherently vulnerable: the very openness that allows stem cells to self-renew and differentiating cells to reprogram their transcription also exposes the genome to instability. Conversely, excessive rigidity would prevent the transitions that spermatogenesis requires. Hence the double-edged sword of the title.

The review also draws attention to the germline’s relationship with transposable elements, the mobile genetic sequences, including endogenous retroviruses and LINE-1 elements, that litter the mammalian genome. Keeping these elements silent is a perennial task in germ cells, where their activity would be especially damaging because changes would be heritable. Epigenetic silencing mechanisms, particularly DNA methylation and repressive histone marks, are deployed against these sequences throughout the postnatal stages, adding another layer to the stability mandate. The authors’ abbreviation list, spanning everything from fluorescence-activated cell sorting to unit-gravity sedimentation cell separation, hints at the technical sophistication of the field, which now combines cell-type purification with genome-wide epigenomic profiling to dissect individual stages of spermatogenesis that were once studied only in bulk tissue.

What emerges from Schöpp and Mansuy’s synthesis is a picture of the postnatal male germline epigenome as a system in constant, controlled motion. From the formation and differentiation of SSCs, through the mitosis-to-meiosis transition, to post-meiotic maturation and the final packaging of the sperm genome, epigenetic marks are written, erased, rewritten and selectively preserved. The review closes by outlining open questions about how these processes are coordinated across developmental stages and what their biological importance is, acknowledging that the field is still assembling the full choreography. How the three-dimensional organization of the genome is reconfigured at each transition, how retained histones are chosen and what they carry, and how the balance between flexibility and stability is enforced at the molecular level all remain active frontiers. For researchers interested in fertility, in developmental biology, and in the mechanisms by which information travels from one generation to the next, the postnatal male germline has become one of the most instructive systems available, and this review provides a timely map of where the field stands and where it must go next.

Subject of Research: Epigenetic regulation of spermatogenesis in the postnatal male germline

Article Title: The epigenome of the postnatal male germline: A double-edged sword between flexibility and stability

Article References: Schöpp, T., & Mansuy, I. M. (2026). The epigenome of the postnatal male germline: A double-edged sword between flexibility and stability. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06427-3

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06427-3

Keywords: epigenetics, male germline, spermatogenesis, spermatogonial stem cells, DNA methylation, histone modifications, chromatin, spermatozoa, meiosis, infertility, transposable elements, intergenerational inheritance

In a recent open-access article published in Epigenetics Communications, philosopher Emma Moormann of the University of Antwerp reimagines how epigenetic knowledge should be communicated and used in thinking about parenthood. Her starting point is a striking observation about the existing literature on the ethical, legal and social aspects of epigenetics, often abbreviated as ELSA research. Almost unanimously, this literature warns that epigenetic discoveries tend to inspire policies and public discourses that blame and stigmatize individual parents, and women in particular. Narratives about maternal stress, diet and behaviour during pregnancy echo what scholars describe as a long history of society blaming mothers for the ill health of their children. Moormann does not dispute these warnings; she considers them important and correct. Her argument is that they are not the only shape the ethical conversation can take, and that ethicists should also work to imagine genuinely positive uses of epigenetic knowledge.

The technical heart of her critique lies in the classic conditions for moral responsibility. Philosophers generally hold an agent responsible for an outcome only if three conditions are met: the agent knows or could reasonably have known the effects of their actions, the agent is capable of acting on that knowledge, and there is a genuine causal connection between behaviour and outcome. In the context of epigenetics, all three conditions are problematic. Political scientist Maria Hedlund has argued that the structural conditions shaping epigenetic health often lie beyond the capacity of individuals to influence, and that acting in an epigenetically responsible way would be a demanding task for any single person given the complexity of the relevant information. Epidemiologists Bastiaan Heijmans and Jonathan Mill have catalogued the biological, technical and methodological obstacles that make it extraordinarily difficult to isolate the effects of individual behaviour on the epigenome. The causal chain between a parent’s choice and a child’s health outcome is tangled, probabilistic and context-dependent.

These difficulties deepen when the role of social circumstances is taken seriously. Epigenetic mechanisms are sensitive to social determinants of health such as poverty, pollution, housing and occupational stress, and these are distributed very unequally across societies. Luca Chiapperino has extended the critique of individual responsibility by pointing to the influence of moral luck, the way factors beyond one’s control affect the justification of responsibility claims. Crucially, he shows that the same critiques apply to collectives: knowledge, capacity and causality conditions are just as hard, if not harder, for collective agents to fulfill. Meanwhile, researchers such as Charles Dupras and Vardit Ravitsky warn against both simplistic individual blame and simplistic state-focused solutions, noting that the very definition of a normal or healthy reference epigenome is contested. According to the mismatch model of epigenetic disease development, an adverse phenotype depends not merely on the presence of a specific epigenetic variant but on the mismatch between that variant and a person’s living conditions, meaning the full impact of any epigenetic alteration can only be assessed contextually.

Moormann argues that these persistent obstacles justify a pragmatic shift: alongside continued work on responsibility, ethicists should explore approaches that do not hinge on the concept of responsibility at all. She frames this through the lens of nonideal theory, a style of normative reasoning that refuses to assume just background conditions and instead takes seriously the unequal distribution of social, economic and material resources among parents. Nearly half of all pregnancies worldwide are unintended, gender inequality still concentrates the burdens of reproductive health on women, and many families lack the means to secure healthy food or a clean environment. General statements about the responsibilities of all parents risk adding insult to injury. Instead, Moormann proposes focusing on empowerment, drawing on the political philosopher Iris Marion Young, who distinguished a purely individual notion of freedom from a dialogical, collective one in which relatively powerless people come to understand the social sources of their disadvantage and act together to change them.

The most provocative part of the paper is its proposal to connect epigenetics with narrative identity, the internalized and evolving story of the self that a person constructs to make sense of their life, a concept developed by psychologists such as Dan McAdams. Moormann illustrates the idea with hypothetical cases. In one, a postdoctoral researcher named Farah continues her stressful academic career during pregnancy; ten years later her son Alex is diagnosed with ADHD, a condition for which some epigenetic evidence links prenatal stress to offspring outcomes. Rather than blaming his mother, Alex might, through honest conversation about her reasons, values and constraints, come to understand her choices and integrate the story into his own sense of who he is. In another case, a child named Jenn learns that her parents moved away from a polluted neighbourhood before her conception, and that inherited marks of that exposure may still influence her susceptibility to conditions such as asthma. Such knowledge could contextualize her biology within her family’s biography.

What epigenetics specifically adds to this project of identity formation, Moormann argues, is an expanded timeframe and scope. Intergenerational epigenetics suggests that marks sustained long before conception may persist across multiple generations, while environmental epigenetics reveals that less visible influences such as stress can shape biology in ways previously unappreciated. This gives people a wider menu of potentially relevant elements for their life stories, from which they can select and edit as they see fit. Importantly, absolute etiological certainty is not required. The stories people tell about themselves are always partly speculative, as philosopher David Velleman has observed in reflecting on his own family history, and the epigenetic component of a biography need not be quantified or absolutized to be meaningful. Some Indigenous communities have already found environmental epigenetics a helpful framework for linking ancestral experiences of slavery and dispossession to contemporary bodies and health, and researchers have debated whether descendants of Holocaust survivors carry a kind of biological memory of trauma.

Moormann is candid about the risks of her proposal. The first is overweighting etiology: knowing the causes of a condition is not always necessary or even desirable for living well with it, a point emphasized by neurodiversity scholars, even though some autistic people do welcome biological research as a basis for diagnosis. The second risk is bionormativity, the culturally dominant assumption that biological ties are what matter most in family life. Talk of maternal and paternal epigenetic influences must not gloss over adoptive families, surrogacy, assisted reproduction and stepparenting, and Moormann endorses the view that nothing important need be lacking for a child raised without a biological connection to their parents. She also cites philosopher Daniela Cutas, who suggests that epigenetics may actually broaden the category of biological parenthood, since everyone closely involved in raising a child helps shape the child’s environment and, through gene expression, their molecular biology. If empowerment language is misused, it can also serve a neoliberal agenda of devolving health responsibility from states to individuals, a warning issued by Chiapperino and Giuseppe Testa.

The conclusion Moormann reaches is a call for creative, compassionate science communication. Because epigenetic research is advancing rapidly and already influences public and political debates, ethicists cannot limit themselves to issuing warnings; they must also articulate positive alternatives. She suggests empirical research into how people actually feel about epigenetic knowledge, and novel dissemination methods such as storytelling podcasts and artistic projects that convey the complexity of biosocial influences without deterministic exaggeration. If epigenetic findings are framed carefully, conversations between parents and children about inherited exposures could foster self-knowledge, mutual understanding and a shared recognition that health is socially embedded, perhaps even motivating collective action against pollution or injustice. The double-edged sword of epigenetics, on this view, need not always cut toward blame. Wielded with nuance, it could help families weave biology and biography into a single, more forgiving story.

Subject of Research: Ethical and social implications of intergenerational epigenetic knowledge for parenthood and science communication

Article Title: From parental responsibility towards mutual understanding: reimagining the employment of epigenetic knowledge

Article References: Moormann, E. (2024). From parental responsibility towards mutual understanding: reimagining the employment of epigenetic knowledge. Epigenetics Communications, 4(1), Article 3. https://doi.org/10.1186/s43682-024-00026-8

Image Credits: AI Generated

DOI: 10.1186/s43682-024-00026-8

Keywords: epigenetics, intergenerational inheritance, parental responsibility, narrative identity, bioethics, science communication, nonideal theory, empowerment, social determinants of health, bionormativity, DOHaD, procreative autonomy