Once my cousin came to my place and ask my dad about marriage. They were young and they asked about whether they are old enough to marry.
My dad's response is "if you find classic musics as to be good to your ears, that means that you're matured enough".
I do agree with my dad's statement and even though it might not be 100% true, it does reflect your maturity in a way.
As for the music, those singers and musicians would tend to produce music that reflect their age and maturity. Look at Lady Gaga and Dave Matthews Band.
I would say that I'm not that matured as I do love 3OH!3 but I also love Elvis Presley (Suspicious Mind).
p/s: I'm envious of my friends who are getting married.