I've realized just how lucky I am to have parents who just don't give a shit. Indeed, if it had a negative effect on my schoolwork, I would, without question, cut it back myself. But, honestly, most parents are ignorant (or perhaps miseducated would be a more precise term of art) about marijuana. It all goes back to their generation being duped into thinking pot is "evil" by the Nixon administration using a war on drugs to distract the public from the failure of Vietnam.

If you rationalize with your parents and say something to the effect of: "Look, I enjoy smoking this, and it doesn't have a negative impact on my life. You've been duped by the system, and you need to put this aside before your bullshit misconceptions about harmless fun ruins our relationship."

That's what I did with my parents, and it's never been an issue. In fact, it has become a matter of jest with my father, who refers to me as "Smokey" and asks me, quite often, if I've "smoked a bowl lately?" If I get pissed off about something, he says, "Hey, I though you fucking potheads were into nonviolence. Go hit the bong, spaceman."

Point is, people can be talked to. Just have a heart to heart with mom and everything will be fine. I don't want to see your relationship get fucked because of a few harmless drugs.