Genetics vs. Epigenetics: What’s Written in Stone and What Isn’t
When people hear the word genetics, they often think of irreversible traits they inherited from their parents. Things like eye color, hair texture, and even diseases that run in the family. But what if I tell you there is more to genetics? Yes. It’s true. You inherit genes and DNA from your family, but you can influence how those genes behave. The process of influencing how the genes behave is called epigenetics. The difference between genetics and epigenetics is both fascinating and empowering. Let’s get to the bottom of this difference.
The Basics
Before diving into genetics versus epigenetics, it helps to understand the foundations: DNA, genes, and chromosomes.
Nucleotides – These are the building blocks of DNA and RNA. There are four: adenine (A), thymine (T), guanine (G), and cytosine (C). These four nucleotides make up your DNA.
DNA – Short for deoxyribonucleic acid, DNA consists of millions of nucleotides arranged in different combinations. Together, they form the famous double helix structure (imagine a ladder twisted into a corkscrew). The rungs of the ladder are the nucleotides paired together: A always pairs with T, and C always pairs with G.
RNA – Short for ribonucleic acid, RNA is a single strand of nucleotides that provides the working template for protein production. Life cannot exist without functional RNA, not even the simplest microorganisms.
Genes – Genes are specific segments of DNA that provide the instructions for making proteins or functional RNA.
Chromosomes – DNA doesn’t float freely in the cell. Instead, it coils around proteins to form chromosomes. Humans have 46 chromosomes, arranged into 23 pairs. Half come from sperm and half from egg. These chromosomes are housed in the nucleus of almost every cell in the body.
So, to put it all together: four nucleotides combine in infinite ways to create genes, which make up our DNA. DNA wraps around proteins to form chromosomes, the organized package that carries all of our genetic information.
Genetics: The Blueprint
So now that we understand the basics, genetics is the study of the genes that we inherited. Some genetic conditions are written into this blueprint from birth and are largely unchangeable. For example:
Cystic fibrosis is caused by mutations in the CFTR gene, leading to thickened mucus in the lungs and digestive tract.
Sickle cell disease results from a single DNA alteration in the hemoglobin gene, altering the shape of red blood cells.
BRCA1 or BRCA2 mutations significantly increase lifetime risk of breast and ovarian cancer.
When expanded, genetics also address conditions that do not have the expected 46 chromosomes such as:
Down Syndrome is caused by having an extra copy of chromosome 21. This happens because chromosome 21 did not separate properly during the development of an egg or sperm during formation.
Klinefelter syndrome occurs in males who have an extra X chromosome, resulting in a 47, XXY rather than a 46, XY. This can cause infertility along with some other health issues.
Turner syndrome occurs in females who are missing all or part of one of their X chromosomes. Instead of 46, XX, they often have 45, X, which can result in infertility, heart and kidney problems and other issues.
While you cannot change the nucleotide structure of genes or override some genetic conditions as described above, you do have a lot of control over how some of your other genes are expressed. This is epigenetics.
Epigenetics: The Dimmer Switches
If genetics is the blueprint, epigenetics is what happens once the blueprint is built. Epigenetics doesn’t rewrite the letters of your DNA. Rather, it influences how your body reads them.
One way to picture it is to think of your genes as the lightbulbs in a house. They’re wired in when the house is built, and their presence doesn’t change. Epigenetics acts like a dimmer switch. Some lights can be turned on, some dimmed, and others switched off entirely.
This is where environment, behavior, and lifestyle step in. Stress, diet, exercise, sleep, and even exposures like pollution can all flip those switches; sometimes brightening a gene’s effect, sometimes dimming it, and sometimes shutting it down altogether. In other words, while we may not control the wiring or the location of the light, we do influence how the lights are used.
Examples include:
Identical twins: Born with the same genetic blueprint, but as they age, their risk of disease often diverges depending on lifestyle and environment.1-4
Smoking: It doesn’t rewrite DNA, but it adds chemical “tags” known as methylation that can switch on genes driving inflammation and cancer. These changes can occur as early as in utero in women who smoke while pregnant.5-7
Alcohol: Drinking alcohol can also influence gene expression, leading to a variety of conditions in the liver, heart, blood, and brain.8-11
This matters because while you can’t rewrite your DNA, you can strongly influence how your genes are expressed. Your daily choices play an enormous role in health outcomes, even if you were “dealt” certain genetic risks at birth.
How to Nudge Epigenetics in the Right Direction
Science shows there are practical steps you can take to encourage healthier gene expression:
Nutrition: Multiple studies demonstrate that dietary vitamins (such as folate, B vitamins, vitamin A, vitamin D), micronutrients (such as zinc), and bioactive food compounds (such as polyphenols and organosulfur compounds) can modulate gene expression and alter epigenetic mechanisms like DNA methylation.12-20
Physical activity: Exercise induces similar changes as proper nutrition particularly in skeletal muscle, adipose tissue, and blood cells often improving metabolic regulation, inflammation, mitochondrial function, and muscle adaptation.21-25
Sleep: Both experimental and observational studies in humans and animal models demonstrate that sleep duration, quality, and timing are associated with epigenetic changes.26-28
Stress reduction: Interventions that address stress, such as mindfulness-based practices and psychotherapy, have been shown to modulate epigenetic patterns. Mindfulness and meditation can reverse or attenuate stress-induced epigenetic changes and are associated with increased resilience and improved genomic health.29-32
Social connections: Studies demonstrate that both the presence and quality of social relationships, such as marriage, friendships, and family support, are associated with epigenetic aging markers, independent of other health behaviors and perceived social support.33,34
Avoiding toxins: Limiting exposure to tobacco, excess alcohol, and environmental pollutants reduces harmful gene activation.
It’s no coincidence that these also happen to be the six pillars upon which lifestyle medicine is based. There are no hacks here. No extra supplements. No additional drugs that benefit big pharma. It is simply making meaningful lifestyle modifications.
Real Disease. Real Life.
I can give theoretical examples and beat the horse to death regarding how important lifestyle choices are. However, I think sharing a real life example of a real disease will really hit home. While many examples exist, I find one quite impactful regarding Alzheimer dementia.
Apolipoprotein E is a molecule in our bodies that has three different phenotypes which are genetically determined: 2, 3, and 4. Everyone has 2 copies of apolipoprotein E (APOE) and there is no way to change one’s APOE genetic combination. There is evidence to suggest individuals with the APOE4-APOE4 phenotype are at highest risk of developing Alzheimer’s dementia. Exercise and nutrition influence the epigenetic expression and functional impact of APOE, which modulates the risk and progression of dementia.35,36
I won’t get into the molecular biology of the process because it doesn’t matter. What matters is that people who carry APOE4/APOE4 can influence their progression to dementia based on how they eat and exercise. Let that sink in for a moment. Genetics predisposes people to developing dementia, but they can control development of the disease through lifestyle choices. That’s epigenetics. Think of how many lives could have a positive impact by delaying or stopping the onset of developing dementia.
The Bottom Line
Genetics hands you the cards, but epigenetics determines how you play them. While some conditions are locked into our DNA, many of the most common diseases we face today, heart disease, type 2 diabetes, even certain cancers, are strongly influenced by epigenetic changes. That’s good news, because it means that small, everyday decisions have the power to shift your health trajectory in measurable, lasting ways.
“Disclaimer: Even though I’m a doctor, I’m not your doctorand reading this blog does not establish a doctor–patient relationship. This information is intended for general educational purposes only and should not be taken as personalized medical advice. Always speak with your own healthcare provider before making decisions about your health.”
References
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- Castillo-Fernandez JE, Spector TD, Bell JT. Epigenetics of Discordant Monozygotic Twins: Implications for Disease. Genome Medicine. 2014;6(7):60. doi:10.1186/s13073-014-0060-z
- Bell JT, Saffery R. The Value of Twins in Epigenetic Epidemiology. International Journal of Epidemiology. 2012;41(1):140-150. doi:10.1093/ije/dyr179
- Talens RP, Christensen K, Putter H, et al. Epigenetic Variation During the Adult Lifespan: Cross-Sectional and Longitudinal Data on Monozygotic Twin Pairs. Aging Cell. 2012;11(4):694-703. doi:10.1111/j.1474-9726.2012.00835.x
- Herzog C, Jones A, Evans I, et al. Cigarette Smoking and E-cigarette Use Induce Shared DNA Methylation Changes Linked to Carcinogenesis. Cancer Res. Jun 4 2024;84(11):1898-1914. doi:10.1158/0008-5472.Can-23-2957
- Zeilinger S, Kühnel B, Klopp N, et al. Tobacco smoking leads to extensive genome-wide changes in DNA methylation. PLoS One. 2013;8(5):e63812. doi:10.1371/journal.pone.0063812
- Kaur G, Begum R, Thota S, Batra S. A systematic review of smoking-related epigenetic alterations. Arch Toxicol. Oct 2019;93(10):2715-2740. doi:10.1007/s00204-019-02562-y
- Dumitrescu RG. Alcohol-Induced Epigenetic Changes in Cancer. Methods Mol Biol. 2018;1856:157-172. doi:10.1007/978-1-4939-8751-1_9
- Wu L, Zhang Y, Ren J. Epigenetic modification in alcohol use disorder and alcoholic cardiomyopathy: From pathophysiology to therapeutic opportunities. Metabolism. Dec 2021;125:154909. doi:10.1016/j.metabol.2021.154909
- de Diego I, Müller-Eigner A, Peleg S. The Brain Epigenome Goes Drunk: Alcohol Consumption Alters Histone Acetylation and Transcriptome. Trends Biochem Sci. Feb 2020;45(2):93-95. doi:10.1016/j.tibs.2019.11.002
- Morford KL, Tetrault JM, O’Connor PG. Alcohol and Cancer Risk. JAMA. 2025;doi:10.1001/jama.2025.11229
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