Justin Bieber Undies On Stage -- Good Genes or Good Docs?!

Justin Bieber's looks over the years are UN-BELIEBER-BLE!

Here is a 20-year-old version of the Canadian native presenting in his undies at the Fashion Rocks 2014 event in New York City (left). This was 4 years after he dropped his big bop "Baby."

And more than a decade later, this Zzzaddy is still rockin' undergarments on stage, seen here (right). JB totally rocked out at Coachella this year and owned the spotlight, but we gotta know: Good Genes or Good Docs?!

Lookin' for more Bieber photos? Check out the gallery above showcasing his Coachella performances through the years!