When you say adult, do you mean a middle aged woman or a legal adult at age 18? I'm in my mid 30's, when I was 18 some could have said I wouldn't gtow up to be respectable, I partied, had a problem with authority, was a financial mess, etc however I'm nowhere near the same person I was at that age. I assume Miley and Taylor (even at 21) could both be respectable adults, or either of them could turn out not to be.