Lenny Kravitz

Good Genes

or Good Docs?

7/12/2009 2:01 AM PDT BY TMZ STAFF
Lenny Kravitz may party like a rock star ... but you'd never know it.

Lenny Kravitz
Here's the 25-year-old singer back in 1989 (left) -- and 20 years later, the 45-year-old version in London last month (right).

Are you gonna go his way?