With medical, physiological and biological getting much better very quickly, there are all sorts of rear-guard attacks on the inarguable determinism. The idea that everyday effects can change the genes, along with brain plasticity are two of the most popular. These are not science-based but designed to sooth pop fears about.
Here we dispense with epigenetics:
“adaptive methylation, such as “parental imprinting”, in which the father or mother contributes differently methylated DNA’s, which do different things in the zygotes and offspring, is based on instructions in the DNA itself. That is, the DNA carries instructions that say something like, “If you’re a male, methylate this bit of DNA in your sperm.” That is not environmentally induced or Lamarckian change of the DNA.
Finally, I know of not a single adaptation in organisms that is based on such non-genetic change. Yet geneticists now know the genetic basis of dozens of adaptive traits that differ between populations and species. All reside in the DNA. If non-genetic adaptive change were common, we would have seen it. Finally, it would be odd if pure epigenetic change were the basis of adaptations, because it is not inherited stably. For an adaptation to become fixed in a population or species, it must be inherited with near perfect fidelity. That is not the case for all environmentally-induced modificatons of DNA.”