Mariah Carey: Good Genes or Good Docs?

9/20/2009 5:15 AM PDT
Mariah Carey has hit a high note ... and her voice is really good too.

Here's the 21-year-old diva back in 1991(left) -- and 18 years later, the 39-year-old version at a film premiere in Toronto last week (right).

She really is "Precious."