genetics-some diseases are passed through generations. Alzheimer's disease is a disease passed through genes. it affects someones life by them forgetting. it makes the person forgettable. there is no known cure

environmental-some diseases are caused by the environment they live in. factories can put off smoke. the smoke can cause cancer. in some cases it can be curable. others it is treatable. cancer makes you feel bad and can kill you.

lifestyle- the way someone lives could cause them to have certain diseases. like smoking, smoking can cause cancer. cancer can cause death and sickness. it can be cured through chemo-therapy, which is radiation being directed to the spot of cancer.