- By: Health & Wellness Researcher
- Date: February 12, 2026
- Source:Salk Institute (Nature Genetics)
Do you know why the same virus gives one person mild symptoms but makes another seriously sick?We saw this clearly during the COVID-19 pandemic. Two people could catch the same infection. One stays home with a mild fever. The other ends up in the hospital. Why?Scientists at the Salk Institute say the answer is not just in your genes. It is also written in your life story.
Your own immune system contains a molecular diary that stores information about genes, infections, and vaccinations since the moment you were born. Each infection and vaccination is a way of teaching your own body to react to attacks more quickly and strongly in the future.Your environment, exposure to chemicals, diet, and stress levels also shape how your immune system reacts over time. Together, these experiences form a living biological record that helps your body recognize dangers and protect you from future threats.
What Did Scientists Discover?
Scientists developed a detailed epigenetic map of how human immune cells are regulated, their responses to infections, and their responses to disease.
What does that mean?
All of your cells contain the same DNA, but they are not identical in their behavior. A brain cell behaves differently from your skin cell. Your immune system behaves differently from your brain and your skin.This happens because of something called the epigenome.
What Is the Epigenome?
Think of your DNA as a big instruction book that your body is born with. It has on it all the basic information the cells need to function. The epigenome is like small chemical marks that sit on top of this DNA. These marks don’t change the actual instructions but do control how those instructions are used. They tell your cells which genes should be active and which should stay quiet.
Who Did the Research?
The study was led by Professor Joseph Ecker and his team at the Salk Institute.They studied blood samples from 110 people with different:
- Genetic backgrounds.
- Infection histories (flu, HIV, COVID-19, MRSA, etc.)
- Vaccination histories.
- Environmental exposures.
This enabled them to compare the formation of different immune systems.
Why This Is Beneficial for You
This study has significance since it may lead to more personalized health care in the future. It means that doctors may be able to study your epigenetic markers in the future to understand how your body may react to various infections. They may be able to know and plan how your immune system may react to an infection.
For example, let’s consider the possibility of the discovery of a biological marker that those who easily recover from COVID-19 possess. As a result, doctors could then use biological marker testing for other patients and then tailor treatment accordingly for prevention of severe disease. The technique of precision prevention will help prevent severe diseases from the onset.
Which Immune Cells Were Studied?
- Scientists focused on four major immune cell types:
- T cells: T cells are a kind of white blood cell that helps your body fight infections as well as diseases. These white blood cells recognize as well as destroy abnormal or infected cells, helping you regulate your “immune response.”
- B cells: B cells are white blood cells that make antibodies to fight infection. Antibodies are like markers on your body to remember bad infections early on so your body can fight them in the future.
- Monocytes: The monocytes are a type of WBC that responds quickly to infection and inflammation. They help in destroying germs and thereby activate other immune cells for defense.
- Natural Killer (NK) Cells: NK cells are immune system cells which immediately attack infected or abnormal cells. This acts as the human body’s earliest line of defense, which does not require previous exposure.
They also found that genetics and experiences both influence how well these immune cells work. Some changes may be hereditary, meaning they are passed on in your family because of your genes. Other changes may result from your environment, your lifestyle, your infections, and your stress.
Why Is This Discovery Important?
The researchers found two major types of epigenetic changes:
(1). Genetic-Driven Changes (gDMRs) : Genetic driven changes (gDMRs) result from the genes that you get from your parents. gDMRs are stable, and they last for a very long time. Genetic driven changes have a very significant effect on your memory immune cells; T-cells and B-cells.
(2). Experience-driven changes: Experience-driven changes also known as eDMRs, occur due to things we undergo in our lifetime, like infections, vaccinations, foods, stress, and our surroundings. Experience-driven changes are not permanent. They can change with time.
Why Do Some People Get Sicker Than Others?
It’s becauly. se, over time, immune systems have been shaped differently. Someone with protective genes, helpful past exposure to infections or vaccines, and strong epigenetic markers has an immune system that responds quickly and effective.On the other hand, if a person does not have any of these patterns of protection, he or she would not fight the infection as well, and the disease becomes worse. So, it is not really a matter of luck; it is a biological issue affected by our genetic and life history components.
The Big Concept: Nature vs. Nurture
Health is determined by the genes you got from your parents, and by your experiences through life. Your body’s response to disease is a complex interplay of what you bring through inheritance and your lifestyle.
Final Thought
The immune system is not just a defense, but a living memory of your life. According to research from the Salk Institute, people are not biologically identical in how they fight disease since genes and life experiences entwine to shape immune responses. Past infections, environment, stress, and lifestyle leave marks that influence how the body will react when future threats arise.
