Ziggy looks just hear age imo. I don't think she looks that much older then 20.
You do have a point though. The show is dominated predominantly by late teens e.t.c. But that is clearly the focus tptb want to go in. Shows original premise was centred around fostering. Don't really have that aspect atm. But like you said. A lot of the current characters are under-developed and one dimensional. Justin imo is the most developed Morgan. So I also don't think its just because their is a lack of balance. Its also not character driven as it was pre 2008.