It sounds as though your mother (earlier accounts, or my memories thereof, were unclear--was she also the victim of a toked-up driver?) has been able to put the past behind her. I don't know that you should be quite so resigned to never being able to bring your rational faculties to bear on the issue--I repeat that if you could see the issue clear you could make the best possible case contra to your daughters, whereas if you merely trot out some variation of the RKJ that started this thread unreeling they will, at best, hear you out politely and then make the finger-twirling-at-the-temple gesture when your back is turned, typically a sign that one's arguments have not carried all before them.
You're being a bit hard on yourself when you say "I know that I am a bigot of the worst stripe." Your mind may be rusted shut on this issue; we both know members here whose minds are welded shut in other matters. Finally, as to "happy puffing (if you're inclined)," a rather complex set of largely unrelated circumstances make this impractical for the nonce--and anyway, I'd found by my mid-twenties that it was as apt to make me feel stupid and anxious/depressed as it was to boost my spirits. "Hell," thought I, "if I'm going to get stupid, I might as well get stupid and exhilarated," and hoisted the first (I came to it late) of many tall frosties. But whether or not I take personal advantage of it I do hope I live to see the day when the savage and senseless "war on drugs" abates.
cordially,
{edit: rogue synonym]