Final answer:
Lung cancer in non-smokers can be caused by secondhand smoke exposure, environmental toxins, or genetic predisposition.
Step-by-step explanation:
Lung cancer in individuals who do not smoke can be caused by several factors. One possible cause is secondhand smoke exposure. Being around someone who smokes increases the risk of developing lung cancer. Another cause is environmental toxins. Exposure to substances like asbestos and radon can lead to lung cancer. Additionally, genetic predisposition can also play a role in developing lung cancer.