Environment beats heredity in shaping immunity of humans

For generations, humans have blamed low immunity on poor genes. But a study on identical and fraternal twins shows that environment plays more of a role in determining the immune system’s response than genes.

For generations, humans have blamed low immunity on poor genes. But a study on identical and fraternal twins shows that environment plays more of a role in determining the immune system’s response than genes.

According to Mark Davis, director of Stanford University’s Institute for Immunity, Transplantation and Infection, the role of the environment in shaping immunity is even more pronounced as we age.

To conduct the study, Davis and his team dived into a registry of over 2,000 pairs of twins, compiled over two decades ago.

As many as 78 pairs of identical twins and 27 pairs of fraternal twins were chosen for the study. While identical twins are genetically identical, fraternal twins, like regular siblings, share 50% genes on an average.

The team drew blood from both members of each twin pair on three separate visits and measured more than 200 distinct immune system components.

Examining the samples, the scientists found that in three-quarters of the measurements, non-heritable influences such as toxic exposures, vaccinations, diet and dental hygiene trumped heritable ones when it came to accounting for differences within a pair of twins.

“While genomic variation clearly plays a key role in some diseases, the immune system has to be adaptable to cope with infection, injury and tumour infection…,” said Davis.