How come i have emphysema, but nobody else in the family has it?

Tobacco?: If you smoke, used to smoke, or are exposed to significant second hand smoke, you've got your answer. Alpha 1 antitrypsin deficiency causes emyphysema in non-smokers but is generally inherited. However, you could be an exception.

Smoking and genes: Perhaps you smoke more than your other family members. Perhaps you have a hereditary condition which makes you deficient in an enzyme called alpha1 antitrypsin.