Patrick Dempsey: Good Genes or Good Docs?

Patrick Dempsey will always be McDreamy.

Here’s a 21-year-old version of the super smooth actor at a movie premiere in 1987 (left) and 28 years later ... a more stubbly snapshot of the Grey's God -- who turned 50 earlier this week -- at a charity screening in Los Angeles late last month (right).

911!

The question is…