I wish I knew the answer to this question. I have an older sister who for as long as I can remember has had anger outbursts. Everybody gets angry but hers has been over the top and is often in public settings and so embarrassing to be around. In later years my mom always used to blame her anger issues on her husband, because it is a marriage that both sides rushed into to their regret. But I remember her getting incredibly frustrated in middle school when she couldn’t figure out her math, even with my mom helping her, and my mom used to be a math teacher. I’ve worked with kids who get frustrated when they are having trouble with math, but she would take her homework and rip it into a thousand pieces and throw it all over the room, and I kind of felt like that was immature behavior for a middle schooler.
When she went to take her driving test, she passed the actual driving part just fine but twice my mom had to take her back because she failed the written portion. The questions can be tricky, but when they got back home my mom told me later that she had basically thrown a tantrum at the dmv.
We used to go to the library together because for a while neither of us drove and there was a local one we could walk to. A little bit later on she could drive and so we would drive to a library here or there. Inevitably, when she got up front to check out, and thankfully we each had our own card, she would find out that she had too many books that were overdue or she owed fines and so they weren’t going to allow her to check out any more books until she took care of the issue, and she would throw a fit in front of the checkout desk. That’s when I generally tended to stay back a ways and pretend like I didn’t know her. She still has anger outbursts to this day and I don’t know if it could be some sort of genetic thing because she is my adopted sister, but I suspected it has led to some issues at recent jobs.
I think if I tried to broach the subject with her though it would probably just trigger another episode.