Originally, I was going to ask "How old is Cain Marco as the Juggernaut?"
Then I got to thinking... technically speaking, Cain was always seen as Charles older half/step brother (depending on the version). However, Charles is routinely seen as more aged than Marco, who, without his helmet, is seen to be a man in his early 40s, at his oldest, and usually late 20s to early 30s.
It then occurred to me, that that would likely be the age at which Marco first touched the gem of Cytorakk, and thus was probably "frozen" at that age.
We already know that as an avatar of Cytorakk, Cain needs no food, sleep or even oxygen to survive, making him functionally unkillable. Logically, that would mean he creates no waste chemicals either, and would then not be subject to other metabolic processes. But then, I must ask...
Is he also literally Immortal, as in ageless, and invulnerable to time or entropy?
Cytorakk himself (the other dimensional entity from which the Juggernaut's magic originated) is timeless, that we know...
But are there any canon comics that literally give his avatar, Cain Marco, part or a human version of that immortality?
While we're on it, if someone wishes to take an educated guess at Marco's age, as well, that would be appreciated.
Note: Because they are not based in the same laws, NO film version of the Juggernaut is applicable here. Comic book and cartoon versions only.