Age affects maturity and the ability to accept criticism and responsibility. For some, age is merely an identifier and not an indication of maturity. That is a sword that cuts both ways. Some members, regardless of age, have been here for a long time and have been a joy to interact with. The fact that your brother has been acting in a not so acceptable fashion does not reflect on you.
It is fantastic that you research before making a decision is to be applauded, but be aware that there seems to be more wrong answers than correct ones on the internet.Even here there will be wrong answers but we try to self-police and correct them. Sometime we do and sometimes we miss ones that are not correct. Be careful in your research.
Good luck and welcome to AC.