I'm not sure people are so much born with cancer as much as many are born with a genetic propensity toward it developing later in life. Most everyone's born with normal cells, and cancer happens when normal cells in various places in the body alter their behavior and structure and begin growing at especially fast rates. Genes play a role in many cancers. Viruses in many others. And environmental and lifestyle factors (like smoking) play a role in many more.

Do a Google on lung cancer and read all about it. Its early symptoms are often hard to recognize, which is why it's so deadly because it gets a head start before it's finally treated. Keep trying to quit smoking till you succeed! Lung cancer is awful, and so is emphysema. Both of those diseases are completely preventable if people don't start--or quickly quit--smoking.