Yes. Environmental factors can influence gene expression—the process by which cells use information in DNA to make functional molecules, especially proteins. Diet, physical activity, stress, sleep, temperature, pollutants, medications, and other exposures can affect which genes are more or less active in particular cells.
This does not usually mean that the environment changes the DNA sequence itself. Instead, environmental signals can alter how cells read and regulate existing genetic information. Understanding this distinction helps explain why people with similar genetic variants can sometimes develop different traits or health outcomes.
Genes provide instructions, but cells control how those instructions are used
DNA contains genes, but having a gene does not mean that it is active at all times. Different cells use different subsets of genes. A muscle cell, for example, needs a different collection of active genes than a liver cell, even though both contain essentially the same DNA.
Gene expression is tightly regulated. Cells use molecular mechanisms to determine when a gene should be turned on, turned down, or kept inactive. Environmental signals can become part of that regulatory system.
For example, nutrients can provide both raw materials and signals that affect cellular activity. Hormones can transmit information about the body’s internal state. Exercise changes energy demands and activates signaling pathways in muscle and other tissues. Exposure to certain chemicals can activate cellular stress responses. These signals can ultimately change the activity of particular genes.
The effects are often highly specific. An environmental factor may increase expression of some genes while decreasing expression of others, and the response can differ among tissues and among individuals.
How environmental signals affect gene expression
Several overlapping mechanisms allow environmental conditions to influence gene activity.
One important mechanism involves transcription factors, proteins that bind to regulatory regions of DNA and help control whether a gene is transcribed into RNA. Environmental signals can change the activity of these proteins, which can alter the expression of their target genes.
Another mechanism involves epigenetic regulation. Epigenetic changes affect how DNA is packaged or chemically marked without changing the underlying DNA sequence. Examples include DNA methylation and modifications to histone proteins, which help package DNA inside cells. These mechanisms can make certain regions of DNA more or less accessible to the machinery involved in gene expression.
Cells also regulate gene expression after DNA has been transcribed. RNA molecules can be processed, transported, broken down, or used to guide protein production in different ways. Small regulatory RNAs, including microRNAs, can influence how much protein is produced from particular messenger RNAs.
These processes do not operate independently. Environmental signals can affect cellular signaling, transcription factors, chromatin structure, RNA regulation, and other processes at the same time.
Which environmental factors can matter?
Diet and nutrients
What people eat can influence gene expression through several pathways. Nutrients and their metabolites can act as signals that affect cellular metabolism and gene-regulatory proteins. Dietary patterns can also influence hormones, inflammation, and the activity of microorganisms living in the gut, all of which can affect biological processes connected with gene regulation.
This does not mean that individual foods simply “turn genes on” or “turn genes off.” Gene expression is usually influenced by combinations of nutrients, overall nutritional status, genetics, and other physiological conditions.
Physical activity
Exercise produces changes in muscle energy use, oxygen demand, hormone signaling, and cellular stress. These signals can alter the expression of genes involved in energy production, muscle adaptation, glucose metabolism, and other processes.
Some of these changes occur relatively quickly in response to exercise, while repeated physical activity can produce longer-term adaptations. The precise response depends on factors such as the type, intensity, and duration of activity as well as the individual’s biology.
Stress and psychological experiences
Stress can influence gene expression indirectly through physiological systems such as the nervous, endocrine, and immune systems. Hormones released during stress can activate cellular signaling pathways that affect gene-regulatory mechanisms.
Importantly, this does not mean that a stressful experience permanently rewrites a person’s genes. Gene-expression responses are dynamic, and their duration and biological significance depend on the nature and persistence of the exposure.
Sleep and circadian rhythms
Many biological processes follow approximately 24-hour cycles known as circadian rhythms. Gene expression itself is part of these rhythms in many tissues.
Light exposure, sleep timing, meals, and other environmental cues help synchronize the body’s biological clocks. Disruption of these signals can therefore affect the expression of genes involved in metabolism, hormone regulation, immune function, and other processes.
Chemicals and pollutants
Some environmental chemicals can influence gene expression by interacting with receptors, triggering cellular stress responses, altering hormone signaling, or affecting epigenetic regulation. Tobacco smoke, air pollution, and certain industrial or household chemicals are examples of exposures that can produce biological changes.
The effect depends on the substance, dose, duration of exposure, route of exposure, and characteristics of the person exposed. The presence of an environmental effect on gene expression does not by itself establish that a particular exposure will cause a specific disease.
Temperature and other physical conditions
Temperature, ultraviolet radiation, oxygen availability, and other physical conditions can also influence gene activity. Cells have regulatory systems that respond to changes in their surroundings, helping them adapt to heat, low oxygen, cellular damage, and other challenges.
These responses illustrate an important principle: gene expression is not static. Cells continuously adjust their activity as their internal and external conditions change.
Gene expression is different from changing your DNA
The distinction between genetic changes and changes in gene expression is fundamental.
A change in the DNA sequence—such as a mutation—alters the genetic information itself. By contrast, a change in gene expression alters how much a particular gene is used without necessarily changing its sequence.
Environmental exposures can sometimes contribute to DNA damage and mutations, so the two processes are not completely unrelated. But ordinary environmental regulation of gene expression generally involves changing the activity or accessibility of existing genetic information rather than changing the genetic code.
This is why the phrase “the environment changes your genes” can be misleading. A more accurate statement is that environmental conditions can change how some genes are expressed.
Why the same environment can affect people differently
People do not respond identically to environmental exposures. Genetic differences can influence how cells sense and respond to nutrients, hormones, medications, pollutants, and other signals.
Age, sex, developmental stage, existing biological conditions, behavior, and the amount and duration of an exposure can also affect the response. Even cells within the same person can respond differently because they have different functions and regulatory states.
This interaction between inherited genetic differences and environmental influences is sometimes described as gene–environment interaction. It helps explain why genetic predisposition does not necessarily determine an outcome and why an environmental exposure does not affect everyone in exactly the same way.
Can environmental effects on gene expression be inherited?
This question requires particular caution. Some environmentally induced molecular changes can persist within an individual for a period of time, but persistence does not automatically mean that the change can be passed to children.
For a change associated with an environmental exposure to be inherited across generations, it must ultimately affect the germline—the cells that give rise to eggs or sperm—and survive the extensive reprogramming that occurs during reproduction and early development. Evidence for stable transmission of environmentally induced epigenetic changes across multiple human generations is limited and difficult to establish.
There is stronger evidence that conditions during pregnancy can influence fetal development and biological regulation. However, an effect on a developing fetus is not the same thing as an inherited genetic or epigenetic change.
What this means for health
Environmental influence on gene expression is one reason health cannot be understood from DNA sequence alone. Genes operate within cells, and cells operate within changing biological and environmental conditions.
At the same time, gene-expression research should not be interpreted as proof that people can control all genetic or health outcomes through lifestyle choices. Many traits and diseases arise from complex interactions among numerous genes, environmental exposures, development, chance, and other biological processes. Some genetic variants have effects that are relatively strong, while others matter only under particular environmental conditions.
The most useful way to think about gene expression is therefore not as a simple switch controlled by the environment, but as a dynamic regulatory system. DNA provides enduring biological information, while cells continuously adjust how that information is used in response to signals from inside and outside the body.
Environmental factors can be among those signals—and in some circumstances, their effects on gene regulation can be biologically important without altering the DNA sequence itself.
