Shania Twain: Good Genes or Good Docs?!

Shania Twain's good looks aren't retiring!

Here's a 38-year-old version of the "Man! I Feel Like a Woman" singer performing at the Grand Ole Opry in Nashville back in 2003 (left) and 12 years later ... the now 50-year-old country staple -- who announced earlier this summer that she is retiring from touring -- performing onstage in New York last month (right).