How old was Genie supposed to be?

I'm not quite sure of her age but I do know that she graduating and I certainly hope she wasn't supposed to be no damn 17 years old because (1) she appeared to be in her early 20s, (2) she was in a club where there was alcohol(if I'm not mistaken) and (3) Michael appeared to be at least 25 which would make it statutory rape if she was 17. So I'm guessing that she's about 22. But did they ever actually say how old she really was? Also, when referring to seeing Genie with Michael in Chinatown, what did the grandmother call him?