What should I do if my brother has a low iq?

Ignore it. Iq tests are not very reliable. Genius is 10% inspiration and 90% perspiration! hard work and liking what you do will beat a high iq in a lazy person that hates their work every time.
Brother IQ. Infinite answers here: doesn't mean you have a low iq; doesn't mean he can't function successfully; doesn't mean you should take any particular course of action. Please clarify?