//Hypognosis I have 5 children but only the one younger daughter has ever shown any interest in 'weed' . I know it neither proves or disproves the 'genetic marker' theory. //
I think you've misunderstood me. I was talking about genetic markers associated with schizophrenia, which appears to be a hereditary condition.
By contrast, there are no known genetic factors influencing whether someone might become "interested in weed" or not. If there were, it would be all over the papers in a trice!
Don't rule it out though. I'm sure there was a study about genetic predisposition to like/loathe smoking tobacco. Perhaps lump it in with anything related to smell/taste and, hence, food preferences/hates. The biggest worry I would have, in LeChat's situation, is that a son or daughter would end up hooked on tobacco.