I can assure you that my parents haven't used any drugs, they don't even drink alcohol. Drug use affects your brain, not your future childerns, it's simple biology.
However, i smoked pot 5 times and the last time was ridiculously scary, i saw myself die in third person view and then i exchanged a few words with the devil (my friends have told me that i was unconscious on the floor during the trip). Marijuana can give you hallucinations if you're vulnerable.