Natalie Portman -- Good Genes or Good Docs?

Natalie Portman's always ready for the big screen!

Here's a 15-year-old version of the Academy Award-winning actress for the film "Black Swan" at a movie premiere back in 1996 (left) and 22 years later ... the Harvard graduate -- who celebrated her 37th birthday earlier this week -- looking dolled up at a music festival in Boston last month (right).

Beauty and brains.

The question is ...