Might exposure to second hand smoke during childhood cause an increased risk of lung cancer in my later years?

Yes: Second hand smoking can cause an increased risk of cancer. Google us department of health and human services the health consequences of smoking: a report of the surgeon general. Atlanta, georgia: centers for disease control and prevention, office on smoking and health, 2004.

Yes it can: Secondhand smoke does increase the chance of developing lung cancer, although much less so that actually smoking yourself. Estimates vary, but your risk is probably less than twice that of someone who never had any exposure (as opposed to 20-30 times higher in smokers).