If people are so stupid to give eachother their passwords then let them.
They can't complain "I've been hacked, I lost all my items".

But if a brother and sister share a account I cna totally understand it.

Thats my opinion.
Btw im not sharing if thats what you think now
:o

No.

Can two brothers share a account?

As long as nobody notices that there are two different persons behind an account, nothing can be done - not saying that is's okay. Playing two different characters from one and the same account, though, does not fall into that category.