Sometimes it may be difficult to figure out why your health issues keep coming around. You may eat well, exercise, avoid toxins, supplement correctly, drink plenty of water, and sleep well but illnesses of various sorts still plague you. If you are doing all of the aforementioned and you still are experiencing unfavorable health conditions, it simply may be your genetics. Unfortunately, this may also be hard to determine and certainly hard to avoid. (By the way, if you have a basement in your home, you need to have it checked for radon gas. The second leading cause of lung cancer in the country next to smoking.)
Indeed, there could possibly have been some exposure to a lethal toxin at some point in your life that didn't make itself manifest until later years for some. Most people in the country live in cities where exposure to a combination of many pollutants that some may be may be more sensitive than others. Perhaps this is the reason why so many cancer cures are not known. They don't why it is caused in the first place. Many people live with various types of cancers in which they are totally unaware. Genetics play a role here too.
Genetics should not be an excuse or to blame for every bad health condition but it should be considered. Live a clean life and you are doing the best you can.