Celine Dion -- Good Genes or Good Docs?!

Celine Dion's voice is the second most beautiful thing about her!

Here's a 19-year-old version of the "My Heart Will Go On" singer rockin' brunette waves back in 1987 (left) and 32 years later ... the glammed up gal -- who just turned 51 years old this weekend -- looking her best self at a fashion show in Paris earlier this year (right).

That's the way it is!

The question is ...