KLS,
Bodybuilding is not the cause of your sons' problems. They can be attributable to a number of variables, including, without limitation, the basic growing up from being a boy to becoming a man. Hopefully, these problems will soon pass before there is any lasting damage inflicted on your sons or someone else.
If they aren't already involved in something purposeful for their lives, such as going to college or learning a trade, and you are enabling them to continue in this path by supporting them, then I would suggest that you put your foot down and force the issue with them. They're at an age where if they're not doing something productive with their lives, they're likely to go in the reverse direction. If school isn't in the cards, there are plenty of well-paying trades that can be learned and money to be earned while learning.
If they are doing something productive, then hopefully this problem will pass, through a combination of learning the hard way by getting beat up and possibly facing minor criminal sanctions, as well as maturing and realizing that there are other objectives in life more worthy of their energy.
On a personal note, I've been there, and done that. For me, it did finally become a historical aspect of my life.