My little brother has anger problems?

It seems that your little brother has an anger management problems. A person so young yet so angry is something that needs to handle quickly or it will follow him to adulthood, as with the case of the uncle and greatgrandfather. Try to find the root of the problem. Perhaps some incidents in the past has had an unpleasant effect on him. Deep hatred towards some people might cause him to react the way he did. Or he is just not happy with the way things are run around him. If all else fail, seek professional help.

Seems like he has a short temper span, so you should go take him to see a therapists or a docter, and they'll tell you whats wrong. And if it does seem to run in the family it must be like a syndrom.

I don't know if he has anger management issues, but it does sounds like there is something going on. I would first take a look at a few things: does he get enough sleep (at least 8 hours); does he eat a lot of junk food or sugary foods; when he throws a tantrum, is it because he is mad or because he is not being understood? Is he really mad at the situation he is in, or did something possibly happen at school that he just isn't talking about? I would first start of making adjustments to his sleep schedule and diet. See if that helps. Try to help him communicate better when he is not upset and use the same methods when he starts getting upset. (There are a ton of resources about this online and I am sure he Doctor can suggest some as well). Also, keep in mind that a 9 yr old is starting to have flurries of hormones which will make the situation worse.

I think your parent should bring him for counseling or get an advice from children psychologies.