Can a brother put his brother on a deed without his knowledge? And if so, what if the brother does not want to be on the deed?

Yes, an owner of a property can add anyone to a deed, even without their knowledge or consent. If someone adds you to their deed and you don't want to be an owner then all you have to do is prepare a new deed transferring your ownership interest back to them.

Why would they give you part ownership

And why would you not want it,

Where is this at