This discussion may contain spoilers!
We learned early on in season 1 that Lee is 37.
We also learned that Clementine is 8 at the beginning of season 1 and 9 at it's conclusion.
It seems reasonable to assume that Larry is around his mid to late 60's.
And Chuck to be in his late 50's to early 60's.
But Kenny's age is something of a mystery.
I would guess him to be early to late 40's, or possibly even early 50's.
If I had to be precise, I'd say 45.