The Environment and Our Genes

Epigenetics is a newly emerging branch of genetics that studies how external environmental factors can affect our genes. It is defined as the “cellular and physiological phenotypic trait variations that are caused by external or environmental factors that turn genes on and off.” Scientists at a lab in Tel Aviv have discovered that “small RNA inheritance” determines the regulation of cells in between generations. They also found that when an organism is in a stressful environment i.e. lacking adequate food supply, small RNAs are passed down to the offspring. As a result, the progeny were better able to handle environments that lacked adequate amounts of food. These genes are able to be turned on and off because of a “feedback interaction” of the small RNAs. Researches are now beginning to turn their attention to human genetics to determine whether we possess an on and off switch that activates epigenetic marks. These marks can be chemical and in this process the DNA sequence is methylated (addition of a methyl group). 

 World War II has given scientists insights into the affects of famine on humans and their offspring. They found that not only did the famished women during the war have children with low birth weight, but the children of those children were also underweight at birth. Healthy unfamished women were still having underweight children even though they were healthy and this led to scientist concluding that something else was at work in this case. The researchers also found that the incidence of schizophrenia also spiked after the war. Compared with other nearby unfinished regions, the famished blockaded town had a much higher rate of schizophrenia among children. 

Not only can the food availability affect future generations, but the lifestyle of parents can affect the health of their children and grandchildren. Things like smoking have also been found to affect the health of children due to epigenetics. When a mother smokes while pregnant, a small molecule is added to a gene that inhibits its function. This may be the reason why children of mothers who smoke are often underweight at birth. Having a better understanding of epigenetics can allow us to understand how the lifestyle choices we make today can affect future offspring.