Here's why:
* He's a child: Charmy is portrayed as the youngest and most immature member of the Chaotix, often acting childish and naive.
* He's small: Charmy's physical stature is significantly smaller than other characters like Sonic or Knuckles, further suggesting he's younger.
* Comparisons to other characters: Vector, Charmy's teammate, is often described as being in his late teens or early twenties. This suggests Charmy is considerably younger.
However, it's important to note that these are estimations based on visual cues and character behavior.