Can anger or negative thoughts influence your health? Or do you believe that factors outside 
of you (stress, environmental issues) or inside of you (within your genetic code) cause illness to occur?
The answer may be a little of both. DNA within individual cells can mutate due to internal and external factors, which leads to a change in the way the cell acts.
Mutation is an inevitable and fundamental property of DNA: changes occur by chance when DNA is replicated and passed on to the next generation, and this process can be affected by factors in the environment. Fortunately, most changes have no effect whatsoever. A tiny fraction are harmful and can lead to cancer or genetic disease, and an even smaller proportion are actually beneficial, and provide the raw material for evolution. http://pub.nsfc.gov.cn/sficen/ch/reader/create_pdf.aspx?file_no=200901037&flag=1&journal_id=sficen
Thousands of changes occur to our DNA daily, but for the most part, mutation is corrected through a series of processes called DNA repair. In fact, less than one in 1000 changes in DNA result in mutation. http://www.ncbi.nlm.nih.gov/books/NBK26879/
The Mind/Body Connection
While the medical industry has not come out directly and said that your state of mind has a direct impact on your health, many acknowledge the mind/body connection.
“It is not a question of whether an illness is physical or emotional, but how much of each,” Dr. F. Dunbar, author of Mind and Body.
Does Anger Cause Heart Disease?
If you believe you are chronically ill or you believe you have a propensity towards a certain disease or condition, you will.
In an observational study of nearly 100,000 women, those with a pessimistic, cynical disposition developed more coronary heart disease, had more heart attacks, and died earlier than optimists. Cynical women were also more likely to develop cancer. http://www.theatlantic.com/health/archive/2012/02/do-negative-emotions-stress-and-anxiety-lead-to-heart-disease/251540/
A Healthier State of Being Begins with a Healthier State of Mind
The first step in your path to better health is to eliminate the stress factors in your life that cause you to feel angry. You are probably saying, “Easy for YOU to say!” Here’s the thing, if you can learn to react differently to these situations, it eliminates the “fight or flight 
syndrome,” (sympathetic nervous system) and creates less stress on the body. Instead of screaming at other drivers who have cut you off on the highway, why not try some deep breathing instead, or sing a song? Remember, reactions and feelings begin inside your brain, which creates a chemical reaction inside your body. A happy or relaxed state of mind causes the parasympathetic nervous system to engage, and the body can then begin to heal itself.
Dr. Lissa Rankin, MD, author of Mind Over Medicine: Scientific Proof That You Can Heal Yourself, and The Fear Cure, breaks down the self-healing process into six steps:
- Believe you can heal yourself.
- Find the right support.
- Listen to your body and your intuition.
- Diagnose the root causes of the illness.
- Write the prescription for yourself
- Surrender attachment to outcomes
For more on the subject visit http://zenhabits.net/heal/. To hear Dr. Rankin present her findings live on Ted Talks please visit: https://www.youtube.com/watch?v=LWQfe__fNbs.
Wishing You Health and Happiness!