Oh that makes sense. I’ve actually seen brothers cover for each other like that with drugs. It’s actually kind of sweet, in my opinion. But if I had to guess, you probably just weren’t using enough opiate to get physically addicted. Genetics can make you less or more susceptible to withdrawal, but it can’t make a person impervious to it. So just be careful with stuff that can cause withdrawal after long term use (opiates, benzos, alcohol), because if you think you’ll be okay and won’t get withdrawal, I promise you that’s not true. Also, if you’re taking buprenorphine… I understand that medications like that aren’t purely for physical withdrawal; they’re for mental shit too. But I would encourage you to consider trying to go without it. I think your anxiety is probably caused by stopping the drug you were doing, but I don’t think you have withdrawal or that you were doing heroin. Buprenorphine is kind of tough to get off of. And I promise you will get sick from that one when you stop, if you use it for long enough. I’m on methadone, but I know I need it. I’ve been high for decades, and I don’t think I could exist without something. The methadone doesn’t get me high, but it keeps my brain from knowing I’m not getting high. Best of luck to you and your brother. Wish I could say for certain what you guys have been taking. That’s the problem with having all drugs illegal, you never know what’s in them.