Ryan Gosling -- Good Genes or Good Docs?

Ryan Gosling's good looks are crazy, stupid, hot!

Here's a 21-year-old version of the 'The Notebook' star showing off his baby face at Sundance back in 2001 (left) and 17 years later ... Eva Mendes' baby daddy -- who turns 38 years old tomorrow -- at an event in Beverly Hills last week (right).

If he's a bird, I'm a bird.

The question is ...