As you know, there's plenty advice about the benefits of giving up smoking and how, for many ex-smokers, symptoms soon improve - after a few years the risk for cancer and heart attacks reduces towards those for lifelong non-smokers.
It's harder to say what long term damage has been done by passive smoking as a child. My Dad ( a GP ) was a heavy smoker - yes, he should have known better, but he didn't know when he became addicted to cigarettes what we know now. However, if you are a lifelong non-smoker (like me) then the chances are that you are now at only slightly increased risk.