I agree with cmorris, and I would go one further and say that the bank has NO LIABILITY about what may happen. They do not dig into your personal life to find out if you are opening an account with a spouse, girl/boy friend, parent, sibling, friend, etc. You can open an account with anyone you chose. They are not going to monitor your relationship and warn you that your brother might steal your money.
Their only responsibility is to inform you of banking rules, service charges, and other things that are in the disclosures you received when you opened the account. Anything else is a personal matter between you and the person you opened an account with.