Fact or Myth: What’s More Important When It Comes to Your Immune System—Nature or Nurture?

Nature over nurture is a Myth.

The idea that our genetic blueprint predetermines our health and longevity is fatalistic and made more of myth than actuality. We have far more control over how our immune systems evolve and what diseases develop than we realize. While the immune systems of young children are certainly more influenced by the genes inherited from their parents, this influence tapers off the older we get, as our immune systems become shaped by the foods we eat and the environments we live in far more than by any hereditary factors. A 2015 study from the academic journal Cell showed that environmental exposures and nutrition—not genetics—are the primary molders of the immune system, especially as we age.

immune_systemIt’s 75% Nurture

A Stanford University research team led by Stanford immunologist Mark Davis sought to resolve whether immunity is determined more by nature or nurture. Researchers studied 78 pairs of identical twins (a 100% genetic match) and 27 fraternal twins (with no more genetic similarity than regular siblings) ranging in age from 8 to 82. They drew blood samples from every participant and analyzed the samples for more than 200 activities and components of the immune system.

Astonishingly, in 75% of the measurements, the identical twins had observable differences due to non-genetic influences, including nutrition, previous infections, and precious vaccinations. Only 25% of the measurements hinted at any link to the genes, and these were mainly found in the youngest twins whose immune systems were still developing.

For example, the oldest sets of twins (60 years and up) showed the most differences in their immune systems, whereas the youngest pairs of twins (younger than 20 and with immune systems not fully developed) had the most similar immune systems. This difference can be understood from a “nurture” standpoint. As the twins age and go on to lead separate lives, in separate environments, with separate conditions, viruses, bacteria, medicines, and treatments, their immune systems change in very separate ways.

The researchers also discovered that when they gave the flu vaccine to pairs of twins there was no evidence that genetics played any role at all in how many antibodies were produced. The researchers also discovered an interesting result with the Cytomegalovirus, or CMV. CMV is a common virus that lays dormant in many people, but can be dangerous in others, such as those with fragile immune systems. In examining 16 pairs of identical twins where only 1 twin had CMV, researchers discovered that there was a significant difference in the immune system in nearly 60% of the variables studied.

Understanding the real winner in the nature or nurture debate can help shed light on the development of diseases, even those one has a genetic proclivity for. According to experts such as Dr. Megan Cooper, a pediatric immunologist and rheumatologist at Washington University School of Medicine in St. Louis, who wasn’t involved in the study, diseases such as autoimmune disease are linked to genetics, but whether or not a person will actually end up becoming sick from the disease may just be shaped more by environmental exposures.

Perhaps the nugget to be taken from this groundbreaking study is that if your family history is plagued with a certain disease to not despair. Eating the right foods, engaging in naturopathic treatments, exercising, and living healthy may stave off the illness during your lifetime.