Few weeks ago journal Cell published a study that was widely publicized by online media. The research article came from Mark Davis lab at the Stanford University School of Medicine.
The authors analyzed cellular and serum immune markers in monozygotic (MZ) and dizygotic (DZ) twins to assess the relative contribution of heritable versus non-heritable factors.
The authors found between 58%-77% of analyzed immune markers are mostly or solely determined by non-heritable, environmental factors. These data suggest that one cannot predict the magnitude and class of the immune response (TH1,TH2,...etc) based on inherited gene analyses. In other words, these results would make studying immune-related therapies, like vaccine efficacy or anti-tumor immunology, more complicated and unpredictable.
However, these results were expected, anyway. The point is that immune system and especially the antigen-specific repertoires of adaptive immune system (TCR and BCR) are generated stochastic fashion, even in MZ twins. Unique adaptive immune system affects innate immune system as well. Basically, no humans would have the same immune system, ever. These implies that neither genes nor environment could truly influence or determine the true direction of immune response. It will be random and individualized response. Only immune system and neuronal system have this additional, random, person-specific level of variation.
Interestingly, the authors themselves acknowledge this point in the discussion, however they dismissed it, as not sufficiently significant.