Brooke Shields -- Good Genes Or Good Docs?!

Brooke Shields' beauty is never blue!

Here is a 14-year-old version of the stunning star at an event in New York City back in 1979 (left). This was just one year after her leading role in Louis Malle's film, "Pretty Baby".

And, 41 years later ... Brooke -- who is spending this weekend celebrating her 55th birthday and shared this eye-popping bikini selfies on IG earlier this week -- was last spotted attending a show in New York City earlier this year (right).

From the '80s classic "The Blue Lagoon" to shows like "Suddenly Susan", "Lipstick Jungle", and "The Middle" ... this famous face has been something to admire for 4 decades!

Shields your eyes!

The question is ...