Environmental Factors Alter Gene Expression: Epigenetics and Its Impact on Health and Heredity

Gene expression can evolve based on environmental factors, modifying the epigenome. Influences such as diet, aging, chronic stress, pollution, and tobacco can alter gene expression. According to Inserm [French National Institute of Health and Medical Research], this phenomenon can be transient, but some epigenetic modifications are permanent, persisting even after the inducing signal disappears. This is evident in smokers, who retain epigenetic modifications years after quitting. These epigenetic markers can be passed to children and even grandchildren. During embryonic division, cells respond to signals and construct the developing organism. Inserm explains, "The epigenetic markers then put in place must be transmitted during cell divisions, so that a liver cell remains a liver cell and a bone cell a bone cell." During the Dutch famine at the end of World War II, children conceived during the famine had significantly higher rates of diabetes and cardiovascular problems compared to those conceived after. "The epigenetic changes that affected the mothers were passed on to the children. These changes would have allowed the children to better endure the famine, but when food became abundant again, this produced undesirable side effects," according to This is epigenetic [Canadian website]. Epigenetic modifications are materialized by biochemical markers on DNA or histones, proteins that structure DNA. DNA methylation, the most known marker, locks genes, preventing their expression. Other mechanisms involve small RNA molecules and potentially unknown factors. Epigenetic anomalies contribute to disease development, especially cancers, with epigenetic modifications occurring during cell life and division. "The alteration of these mechanisms favoring the transformation of healthy cells into cancerous cells, any epigenetic aberration can be involved in carcinogenesis," states Inserm. Epigenetics may also explain metabolic diseases like type 2 diabetes and cardiovascular diseases, although the mechanisms are still under study. In neurodegenerative diseases, researchers have identified an overexpression of genes that exacerbate the effects associated with Alzheimer's disease. Epigenetic regulation is also suspected in certain mental illnesses. Traumas may leave chemical marks on parents' genomes, potentially transmitting to descendants. A study highlighted an epigenetic marker in Holocaust survivors and their descendants, concerning a gene associated with several mental disorders, as reported by National Geographic. Trauma-induced epigenetic changes could thus be transmitted to the embryo. Evelyne Josse, a clinical psychologist and lecturer at the University of Lorraine, summarized for Le Soir [Belgian newspaper]: "If I experience a traumatic event and do not find the necessary help, it is likely that I will undergo epigenetic modifications. And if I become a mother or father one day, it is possible that my child will inherit it with the consequences on mental health that may go hand in hand..." Epigenetics also offers hope, as epigenetic changes could become therapeutic targets or enable early diagnoses.