Kate Walsh -- Good Genes or Good Docs?!

Kate Walsh's good looks are no private matter.

Here's a 32-year-old version of "The Drew Carey Show" actress sportin' a blonde bob in Los Angeles back in 1999 (left) and 17 years later ... the red-headed "Private Practice" star -- who celebrated her 49th birthday earlier this week -- at a Beverly Hills party last month (right).

Nurse!

The question is ...