Genuine things are true or authentic. When you're talking about people, being genuine has to do with being sincere.
This word has to do with things and people that are true. A genuine blonde is a real blonde — no hair dye involved. A genuine friend is a real friend you can trust when the chips are down. Genuine feelings are real feelings — not fake feelings put on as a show. A genuine hundred dollar bill is the real McCoy, not a counterfeit bill. When something is the real thing, it's genuine.