Let’s say you have a twin who, at birth, was completely identical to you, same gender, appearance behaviour, and so on. Then, one day your parents decide to separate. You will go on to live with your mother, and your twin will live with your father. You were lucky and grew up living a normal, healthy life with access to education, friends and a loving environment. Your twin, on the other hand, didn’t get proper nutrition, lived in a rough area and even started smoking.
If you two met later in life, you’ll find that you two are no longer identical. In fact, you’re probably very different from each other, not just appearance wise, but genetically speaking as well. Your genomes would still be identical, but your epigenetics would be vastly different.
DNA is the set of characteristics and traits passed down from your parents that make you who you are. Your DNA is full of genes, but they aren’t all expressed at once. The epigenome instructs your DNA on what to do, but the epigenome doesn’t change your DNA. It merely decides how much and when some genes are expressed. All the cells in your body have a copy of your DNA in them, but they don’t necessarily know what to do with the DNA. Methyl groups are made from carbon and hydrogen and act as a set of instructions, telling the genome what to be. This is how cells know whether to be a skin cell, a brain cell or an organ. Methyl groups will bind to a gene and tell the gene how much it should express or what not to express. 
To compact the enormous amount of DNA we have into our cells, DNA wraps itself around the histones in chromatin form. How much the DNA can express is determined by how tightly the DNA is wound around the histone. Both histones and methyl groups impact your genes. Methyl groups are more of a switch, telling your cell whether to express this gene or not. Histones are more like a knob, telling the gene how much to express. On your DNA, there are these epigenetic marks, and although your DNA will never change throughout your life, the epigenetic marks will.
The choices you make in your life, such as diet, exercise, alcohol and drug use, will change these epigenetic tags. These tags will decide what genes are being expressed in that moment of your life. They will change often throughout your lifetime, more commonly when your body is going through big changes such as puberty or pregnancy. These tags are essentially what make you different from your twin. If you enjoy exercise and eating healthy, those factors would become epigenetic tags that improve your health. But if you eat fast food every day and the only exercise you do is walking to your fridge, it wouldn’t necessarily matter if your parents were health nuts, as your current decisions would affect you more.
You would have the potential to be healthy, but your decisions would have a bigger impact. It works the opposite way as well. If both your parents are overweight, you would have the gene for obesity. However, if you ate well and exercised, that gene would never be expressed. Epigenetic tags are personal, and scientists used to believe these tags didn’t get passed off to your offspring, which is usually the case. If you have a scar or are in incredible shape it doesn’t mean your child will be some scar-faced bodybuilder. However, there are some epigenetic traits that can get passed down by accident.
When a mother is pregnant with her child, what she eats, if she smokes and if she is stressed out, all the factors will affect her unborn fetus. Epigenetic tags can get stuck on the genome and be passed down from generation to generation, more often the bad tags then the good ones. The issue here is that these tags were never supposed to be passed down. Morally speaking, the decisions people makes for their own life shouldn’t have consequences that affect their innocent offspring. If mom or dad smokes, it’s not okay that the child will have asthma because of their poor choices. Diseases such as diabetes, cancer or heart disease are more examples of negative epigenetic tags that are supposed to be silenced, but instead are inherited. Therefore, obesity is influenced by your environment as well as the state of health your parents are in. The dietary decisions your ancestors made affect you, just as the choices you make will help determine the health of your future offspring.
Because scientists and researchers are discovering more information on how these diseases are inherited, they can develop new treatments to help silence these epigenetic tags. These advancements are incredibly helpful as they can begin epigenetic therapy or other epigenome influencing techniques to treat these diseases. In short, due to the discovery of what causes these diseases, treatments can be made that could cure various cancers, Huntington’s, Alzheimer’s and numerous other diseases.
This field of biotechnology would be best used to identify the negative epigenetic tags so that doctors might be able to rid us of them for good someday. Epigenetics has contributed to the advancement to the world of biotechnology. This research allows us to understand diseases we couldn’t before, and now might be able to create cures. Most of the treatments are still in the early stages of development, as the study of epigenetics is still a relatively new concept, just formulated in the 1980’s. Yet, with the technology and information available today, it seems as if silencing these genes will very likely be in the future.
Sources:
https://www.geneticliteracyproject.org/2016/08/09/will-epigenetics-play-central-role-advancement-precision-medicine/
https://en.wikipedia.org/wiki/Epigenetics
A Super Brief and Basic Explanation of Epigenetics for Total Beginners
http://www.bloodjournal.org/content/127/1/42?sso-checked=true#T1
Picture sources:
http://healthyprotocols.com/2_epigenetics.htm
https://www.khanacademy.org/test-prep/mcat/behavior/behavior-and-genetics/v/gene-environment-interaction