Luke Bryan -- Good Genes Or Good Docs?!

Luke Bryan's looks over the years will make you wanna "Strip It Down!"

Here's a 31-year-old version of the singing stud showing some side eye at Stagecoach Country Music Festival in Indio, California back in 2008 (left). This was just one year after the release of his debut album "I'll Stay Me."

And, 15 years later the singing stud took a break from his judging duties and recently snapped a selfie on the set of "American Idol" ... showcasing his show-ready looks and pearly whites.

On Friday, Mr. Bryan took the stage at Stagecoach and gave the audience his notorious "Shake It For Me" dance moves, but the question is ...