hey shoto!
I don't know how old your son is. I am now 23. I kept steeling money from my parents between the ages of 14-15

. It wasn't a lot of money, just the amount I needed to get cigarettes. They always used to give me whatever amount I wanted (if they had it ofcourse), just that they needed to know what it was for. And, ofcourse, I couldn't go up to my mom at 14 and say hey mom, me and my mates started smoking... please give me some money

. I'm not saying your son is smoking or doing smth bad, what I really wanted to tell you is that it never felt like I was
STEALING. I was pretty mature for that age, but taking some coins from my mom did not seem that bad at all. So, imo, if your presumption happen to be true, you shouldn't be so upset... Kids have weird ways of looking at situations (everything is pink, fine and dandy, puppies never die etc.).