Your Genes and the Environment
This section is about the things you can't change, or only have a little control over. Your genes may or may not be the best gene set for the place you live or for the profession you chose. While it is possible to map your own gene set, and the cost has become almost affordable, most of the sequences in your gene map don't code for anything that science can yet identify. It might just be junk, and it might not be. We do know that you can carry a gene, or a set of genes, that are potentially harmful (or useful); yet because of your diet, environment or lifestyle that potential may never be turned on. So genes map genetic possibility, not necessarily your fate. Diet, smoking and stress may cause epigenetic changes to our genes. How many such changes can be passed on to other generations and for how long these changes persist remains unclear.
If you have diabetes you should read this scientific paper, 
Dietary carbohydrate restriction as the
first approach in diabetes management: Critical review and evidence base; then take a copy to your doctor, if you are not already carbohydrate restricting.
In his book "The triumphs of Experience", George Vaillant suggests that if we look after our health, unless fate deals us an unusual hand, we should all live beyond 85. If you get to 105 or not after that really depends on things like your genes. During the 70 years of the Grant Study, Vaillant says he saw people adopt more than three dietary styles. There was no long run benefit, and in the end the data shows it made no difference. The same is true of high stress in mid-life, and being athletic in mid-life and in having high or low cholesterol at age 50. None of these things made any difference to how long people lived, or to how successful their lives were. The best predictor of how long you will live and how successful you will be, is simple according to Vaillant. Did you mother love you? Something else you can't change now.
If you are exposed to harmful toxins or chemicals, in your environment, it can affect the way the genes in your body work. That can potentially cause mutations in your genes that could lead to future disease. However, for his to occur, you generally need a long term exposure to the harmful substance and this varies depending on the environmental toxin/chemical. Two examples: the female hormone estrogen is now found in waterways everywhere, probably because of the wide use of the oral contraceptive pill. This seems to be causing a decline in male sperm counts not only in humans and it's also causing deformity in fish. The over-use of antibiotics is now causing the contamination of drinking water supplies in many areas. This has the potential to cause an outbreak of antibiotic resistant infections.
