Billy Dee Williams -- Good Genes or Good Docs?

Billy Dee Williams' good looks aren't forced!

Heres a 33-year-old version of the 'Star Wars' actor back in 1970 (left) and 48 years later ... the now 81-year-old father of two was photographed at the 'Solo' premiere in Hollywood this month (right).

"Hello ... what do we have here?"

The question is ...