Do you think we are born with cancer cells or do you think we always do something wrong to bring it on?

Neither. I believe that we are all born with the potential to develop cancer; whether we get cancer is probably multifactorial, the "perfect storm" of environmental and/or hereditary factors. While it is true that many cancers are associated with habits within our control (tobacco, alcohol, poor diet, etc), I do not think that cancer is usually due to things that we have "done wrong".
Sometimes. Some cancers in children we are born with. Most cancers develop later in life and may have genetic predisposition that we are born with (not the cancer but the genetic abnormality). Then throughout life environmental factors play a causative role but not always. Smoking/drinking/ lack of exercise/what we eat/ exposures to chemicals and carcinogens will all play a possible role in causing cancer.