Do you drink alcohol? Why would smoking pot be different? And before you answer that, read my response to the previous comment.
Opposition to marijuana seems to be ingrained in some people, many of them older. Whereas my parents would have never partaken, their sons and grandchildren do. It's generational. For the record, I'm 64.
Last May I was at a party celebrating a law school graduation. Sometime after midnight, there were a handful of 20somethings (a few graduates, their significant others, and their parents) sitting in the backyard after lots of alcohol consumption. At that point, anyone walking by the cluster of people on Adirondack chairs could have gotten high from the smoke cloud. Attitudes evolve and if we ignore changes we can become obsolete ourselves.
A long time ago, the couple with season hockey tickets behind mine, admitted they encouraged their 16yo daughter to smoke pot at home. The mother claimed kids would do it anyway and she felt safer if her kid was at home when doing it.