score:12
The question you ask about is seen below:
Your application has nothing to do with his actions, unless you somehow aided him in anyway to overstay. Also the DS160 explicitly asks about family in the US. If your brother lives in Morocco full time, then no need to mention him here. If the consular officer finds out and has questions they will ask you about it in the interview anyway (where you should be completely honest in whatever they ask, but answer ONLY what they ask). You have a seemingly good travel history and from what you say both financial and family ties in Morocco, that should only make the consular officer feel pretty ok about your application.