This 2015 Baylor human cell study subject was the underlying mechanisms of cellular responses to environmental stressors of cold, heat, hypoxia, and oxidation:

“Because trinucleotide repeats are overrepresented in gene-regulatory proteins, stress-induced trinucleotide repeat mutagenesis may provide a path for the environment to subtly alter gene regulatory networks – with attendant changes in cell behavior – during development, disease, and evolution.”

The study’s overarching framework was that human cells will adapt to best survive in their environment. The study found that the cells’ responses to stress encouraged the creation of mutations in a DNA area that’s:

“The cause of multiple human diseases. This pathway may impact normal cells as they encounter stresses in their environment or during development or abnormal cells as they evolve metastatic potential.”

It’s a logical inference to likewise understand how stressors in a mother’s environment for a developing fetus will cause the fetus to adapt at the cellular level. If, for example, the fetus is stressed by inadequate oxygen – hypoxia – this study shows how cells will adapt in ways that foster mutations and diseases.

When the stressed fetus arrives in a different environment after birth, the newborn’s cells are maladapted to certain aspects of a normal environment – to adequate oxygen in this example. Many of the cells’ adjustments to the old environment persist in the new environment. Pathways epigenetically adapted to best survive during the fetus’ development in the womb may impact the infant’s development in a normal environment.

Researchers could make significant contributions to science by investigating treatments and therapies that potentially reverse causes of epigenetic changes.

http://www.pnas.org/content/112/12/3764.full “Environmental stress induces trinucleotide repeat mutagenesis in human cells”