i never said he was 24... where did i say that? Carl was 10 or 11 when the series started (per the comics i think he was 11 in the show so lets go with 11) season spans over a year, plus the hiatus btw seasons 1 & 2 (dont know if thats been factored how long that was, i dont think it was as long as the 'gap' btw season 2 & 3) lets say it was a few months, that would make him 12-ish at the start of season 2. saying season 2 lasted a yr that would make him 14-ish now at the start of season 3, its been said that Beth (in the show) is about 16, that's only a couple of years older then Carl.
Lori mentioned not finding enough to eat over the winter, so i assume that's affected Carl's growth as well, which couldd explain why he still looks so 'childlike'.
"Oh, so many layers to the Beckett onion, Castle. How ever will you peel them off?" Kate Beckett