Genes passed down from parents can be turned off and on through external factors like the environment.

Genetics, a revolutionary idea, was the notion that we passed on tiny particles that carried packets of information or instructions for building a new organism. It began to be more scientifically understood in the late 1800s.

This was due in large part to the work Gregor Mendel, an Augustinian friar and scientist who conducted detailed studies of how the particles pass on using pea plants. Considered to be the “father” of genetics, his research is covered beginning in junior high science.

Many of you may recall the terms dominant and recessive and working out those lovely Punnett squares. You can thank Reginald C. Punnett for that. He and famed scientist William Bateson founded the Journal of Genetics in 1910. Bateson was deeply interested in the underlying cause of variation and especially in the weird mutations where species grew extra body parts or parts in the wrong location.

The basic idea of genetics is that the DNA code of life has regions called genes, and these genes are instructions for life. If a gene mutates, then changes to the organism occur, be they good or bad. Diseases like sickle cell anemia follow this classic idea of genetics but many diseases and traits do not. Genetics is not as simple as Mendel’s pea studies.

In the past 20 years, a new field has emerged and offers the power to explain not only the root cause of many diseases, which classical genetics could not explain, but also a good deal of the natural variations in populations. It is known as epigenetics, and it is revolutionizing medicine and our views on how we pass down information to our offspring.

I will avoid diving into the details of DNA methylation and histone acetylation and focus on the general idea. Epigenetics is where the DNA directions of life get changed without altering the actual DNA code. External environmental factors like your diet, drug and alcohol habits, and even stress can impact how your genome is read.

Genes can be turned on and turned off by the environment. We now know that these epigenetics modifications can happen in sperm or egg and can be passed onto future generations. The environment and choices your grandmother made may have literally altered your code without actually changing any of the physical DNA sequence. This outside the gene or epigenetic modification of gene expression is already linked to a variety of diseases, especially cancer. I got 192,000 hits when I searched epigenetics and cancer in Google Scholar.

TED is one of my favorite places to visit on the web and a great place to spend some spare time. If you search TED or Google for “Moshe Szyf – How Early Life Experience is written into DNA” you will find a 16-minute lecture on epigenetics that will certainly make you think.

Hopefully that sends you down the rabbit hole and you find yourself searching for more videos or reading in Google Scholar or Science Daily about how this field is adding to our classical view of genetics.

To be continued...

 Dr. Jack Brown is the Paris Junior College Science Division chairman.

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