A familial history of chronic diseases tends to have people concerned about what their future might hold. Sometimes it feels as if you’re helpless against the future of your health.
I’m here to tell you that you have more control than you might have originally thought. Genetics play an important role in how we are expressed in the physical world, but they can be altered. You see, our genes are only partially expressed.
Your body expresses genes based on the environmental signals that are presenting themselves to you. This includes: the air that you breathe, the chemicals that come in contact with your skin, the thoughts that cause you stress, the food you eat, etc.
Genes that are passed on to you are not the only indicator of whether you will develop a certain disease or not. This is the relatively new field of epigenetics. Although I’m no expert, I am going to outline a few aspects of disease that are in your control. I will cover a few diseases and the common (often avoidable or reducible) mechanisms that cause them to develop.
Heart disease has been a major topic of discussion in the health field over the past 60 years. With that discussion has come inconceivable confusion and misinformation. Most of the misinformation came from the fact that scientists jumped to conclusions about certain ideas without enough evidence to support them.
Here’s what we know to be the true indicators or contributing factors…
One way that insulin resistance is caused is by over consuming carbs (especially sugars) frequently. The constant response of insulin to regulate the rising blood sugar levels can actually damage the cycle. Your cells begin to require more insulin to have the same effect (ie. The cells become resistant to insulin). This also damages the cells which produce insulin.
Insulin resistance has been linked with chronic inflammation.  Each of these conditions contribute to each other. However, in terms of heart disease risk, inflammation is the key driving force.
Inflammation is necessary to life. It’s an immune response to infection. It protects us from invaders. The problem comes when there’s a sustained level of inflammation circulating throughout the body.
Cholesterol is one of those misunderstood ideas that scientists past pushed as the end-all-be-all to heart disease. For me to show you the counter argument, it’s important to understand some basics. Think of LDL (low density lipoprotein), HDL (high density lipoprotein) and VLDL (very low density lipoproteins) as cars on a highway (the blood). The lipoproteins are just vehicles to transport the cholesterol (the passengers) throughout the body. Therefore when you hear “LDL cholesterol”, that just means the amount of cholesterol within low density lipoproteins.
Cholesterol is essential to life. There is no “good” or “bad” cholesterol. ALL cholesterol is essential. It is the precursor to so many hormones that without it, you would suffer or die. It was once believed that cholesterol was a main contributor to heart disease. It’s now known that cholesterol and lipoprotein count are not good indicators of risk. What is a good indicator is the low density lipoprotein particle size.  It turns out that this metric is a good indicator of inflammation within the body. Again, inflammation is the underlying cause and inflammation is greatly impacted by your environment.
Cancer is a tough one, since there are so many contributing factors (whether discovered or still undiscovered). Still, one of the major factors that is in your control is inflammation. Inflammation can come from many sources.
ROS or reactive oxygen species are generated as by-products during mitochondrial electron transport.  Lifestyle has a large impact on the level of reactive oxygen species someone is able to regulate. The function of antioxidants is to regulate ROS and limit the amount of damage that they are creating.
Levels of ROS contribute to increased oxidative stress on the body which can also contribute to higher levels of inflammation. Inflammation can in turn lead to increased production of ROS which leads to the progression of cancer. 
Another important aspect in the generation of inflammation (and therefore cancer) is the liver’s ability to detoxify the body.  The liver does have a limit though. After a certain amount of detoxification, the liver can no longer filter out the excess toxins. Failure to detoxify can cause inflammation, leading to ROS production which can lead to cancer.
And finally, although not as proven scientifically, insulin resistance can also contribute to the generation of cancer. Scientists are beginning to slowly draw a link and it makes sense, since as discussed above, insulin resistance can contribute to chronic inflammation. 
Alzheimer’s is a big topic. New research is beginning to come out showing how Alzheimer’s disease may be inked to insulin resistance. There is so much of a link that it’s being called “type 3 diabetes”.  The reason that they call it this is that when blood sugar is high (which is the case with diabetes), the excess sugar starts binding to free proteins in the blood to form what are called advanced glycation end-products (AGE).
These AGE are thought to be a major contributor to the plaques that build up in the brain to contribute to Alzheimer’s. 
This isn’t the only big contributing factor with Alzheimer’s Head trauma is also very indicative of potential risk. Damage from head trauma leads to inflammation which leads to more oxidative stress which is also associated with Alzheimer’s. 
As you can see, you are in control of some major factors that influence your destiny. Family history is not the end-all-be-all that we’ve been convinced it might be.
If you should take anything away from this, it’s that inflammation and ROS are at the center of most of our problems. Controlling your environment in a way that optimizes for these aspects will ensure that your genes are expressed in favor of your longevity. Live life looking at every decision as something that will help you, or something that will harm you. Make sure to opt for the former.
 Chris Kresser. “How inflammation makes you fat and diabetic (and vice versa)”. [Online]. Available: https://chriskresser.com/how-inflammation-makes-you-fat-and-diabetic-and-vice-versa/
 ScienceDirect. “Association of low-density lipoprotein particle size and ratio of different lipoproteins and apolipoproteins with coronary heart disease”. [Online]. Available: http://www.sciencedirect.com/science/article/pii/S0914508708001512
 BioTek. “An Introduction to Reactive Oxygen Species – Measurement of ROS in Cells”. [Online]. Available: https://www.biotek.com/resources/white-papers/an-introduction-to-reactive-oxygen-species-measurement-of-ros-in-cells/
 Hindawi. “The Interplay of Reactive Oxygen Species, Hypoxia, Inflammation, and Sirtuins in Cancer Initiation and Progression”. [Online]. Available: https://www.hindawi.com/journals/omcl/2016/3907147/
 NCBI. “Liver immunology and its role in inflammation and homeostasis”. [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4856809/
 NCBI. “The Links Between Insulin Resistance, Diabetes, and Cancer”. [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3595327/
 NCBI. “Alzheimer’s Disease Is Type 3 Diabetes–Evidence Reviewed”. [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/
 NCBI. “Advanced glycation end products contribute to amyloidosis in
Alzheimer disease”. [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC43869/pdf/pnas01133-0166.pdf
 NCBI. “Role of oxidative stress in Alzheimer’s disease”. [Online]. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4840676/