[livi]

Typical case of medical statistics - a concept sometimes a bit confusing to fully grasp if not involved in Health Care.

Yes, smoking is a very potent risk factor for emphysema.

Yes, even if smoking 60 cigarettes a day for your whole life you may very well live until you are 95 without a trace of lung disease.

Yes, genetic disposition is the individual base for all sorts of diseases and some people will have a 'fragility' for developing for example emphysema - or asthma, high blood pressure, angina, osteoporosis, bad temper etc etc. Smoking or not.

Best statistical scenario: Good genes and no smoking.
Next best: Good genes and some smoking
Worst: Bad genes and a lot of smoking

Everything is a lottery however - a statistical lottery that never, ever is applicable on any single individual.