Dylan Efron Good Genes or Good Docs?!

Dyan Efron's stellar looks over the years will make you wanna DANCE!

Here is a 17-year-old version of a shaggy Dylan rockin' curls in Aspen, Colorado for an Audi dinner back in 2009 (left). This was long before he broke through the media as Zac Efron's younger, hotter brother!

And, 16 years later, the shredded star unbuttoned for the cameras at a music festival earlier this year (right). Dylan has brought his chiseled looks to this season of "Dancing With The Stars," and although he's only rang in a couple of 10s ... he's always a 10 in our eyes!

The key question here is: Good Genes or Good Docs?!