My answer is so wishy washy...lol.
No, I do not think that pot is ALWAYS a gateway drug. I know people in their mid-30's and 40's who have never moved on from pot. They like the mellow high pot gives them or in some cases, how it enables them to function day to day in their crazy lives - I should point out that these people would have likely been diagnosis'ed with ADHD as teens! I know a few people also in their later adult years who started with pot, sort of drifted into cocaine use and then went back to just pot and continue to do so. I know people who use pot on a simply recreational basis -at parties, a few times a year.
And then I know a lot of people who smoked it as a teen and then grew out of it (that would be me). I know still others who tried it a few times and it wasn't for them. My sister knows, grows and allows her kids to smoke pot, always has, thinks she's hip and cool and never thought it was harmful in any way. This is the sister whose son is now addicted to barbituates and has another daughter who is a blossoming alcoholic and whose middle daughter just smokes pot, occasionally, more often than not.
My feeling is that it depends on the person and *possibly* the upbringing. I think that if a parent is too accepting about their kids smoking pot then they may be more likely to develop a drug or alcohol problem simply because they were led to believe it's 'harmless'. And then, being here (at CD) for so many years has taught me that so much in our children's development is chemical and completely out of our hands so it may just be a brain chemical thing.
They say that alcoholism runs in families. It supposedly runs in mine. My maternal grandfather, my father, my maternal uncles, my paternal aunts and uncles, my brother, my sister, two nephews and now I suspect one niece. In our home, drug use and alcohol, no matter how minimal the use, has always been discussed as a very serious topic. My exh is a super pothead and as the girls progressed into adolescence it was no secret so I've been able to use him as an example. I've even asked exh to have a chat with difficult child at one point (last year) about pot use and how it can really mess with your life all by itself without being a gateway drug - but of course he pointed out instead how he smokes a little each day and said, "Look at me - I'm okay! Your mom is just worried" (yeah, he's okay all right!). He neglected to point out how his drug use played a very big role in our breakup and with being poor, losing his family, moving 4 times in one year, living on church food, losing jobs and living in a hovel. But I'm getting off track -lol.
So, my answer is "it depends" on the family's attitudes, history, and the chemical makeup of the person using.