Legally, a Canadian may get a mortgage loan here (possibly not an FHA loan, however). Bear in mind that lenders decide on their own who to lend to--i.e. who is a good risk. They make those decisions based on many factors, including credit checks--it is inconceivable that a lender would not do a credit check on a mortgage applicant--and their decisions generally are not subject to review or second guessing, so if lenders choose to not allow you to include your brother in the application or to lend to him, that is their right.