I've found that sometimes flying or driving over high altitude mountain
roads can "clear up" my T. And sometimes it seems to make it worse for a
short time, but never for more than a few days. (I think it's also the
loud noise of the airplane, and the car too. I use musician's earplugs
now, even in movies, and it really helps with the loud sound. And
prevents further damage to my ears.)
I get lots of ear-popping when flying, and follow the advice of a very
experienced pilot: always take a bottle of water on the plane with you
and do a lot of sipping, particularly during take-off and landing. And
at any time during the flight to keep the pressure equalized. Or chewing
gum and swallowing a lot. The water works for me. And it helps with
dehydration due to the very dry air in the cabin.

Smoking grass I don't know about :) But alcohol makes my T _seem_
better, probably because I relax and focus on other things. If you get
really tuned in to your body when you smoke grass, probably your T will
seem louder.

I don't know about T being hereditary, sorry.

I found that my T was helped _immediately_ when I started using a
sound-masking CD at night and, for a while during the day, on my
computer. Now it doesn't bother me too much (1.5 years later), just gets
a bit better or worse on certain days. Being active, focused on other
things and trying to forget about the T is definitely the way to go. I
know it sounds easy, and it's not, but it really works for many people.

Best of luck, Stef