Got permanently banned

I find these excuses quite questionable, as it's the most used excuse on this forums that I've seen over the years when people post up getting permanent ban's,

"oh, a family member or friend was on my account and i got banned because of their actions, it's not fair because it wasn't me on the console"

Whether if this is true or not, your're responsible for your own account or your own actions.

As Smwutches said, in the future, put a password on your account so that this situation won't happen again.

I'm sorry to hear that. What you can do is contacting to the Xbox support to see if there is any possbility to address your situation.

https://support.xbox.com/contact-us Click the link and go to web chat and start to address your issue with the agent.

Per the terms you agree to when you sign up, you are responsible for your account at all times. In the future, if you share a console with your brother, you may want to require a password to log in and don't give him your account information.

Support doesn't handle enforcement issues. You'd need to go to http://enforcement.xbox.com