My response is up here, since I couldn't type once I moved the quote over for some reason:
It's funny, because I think the Aldersons, Kelley Missal, and Shenell Edmonds (Destiny 1.0) were the only regular teens on the show who were ACTUALLY teens in real life, because while Lenny Platt may have been quite a bit older, I think Jason Tam was around the same age, too, even if he otherwise looked younger, and then Brandon Buddy and Brittany Underwood--while not THAT far removed from their teen years at the time--were still in their early twenties compared to the others. So LP was definitely NOT the only adult in a teenage role back then, even if it was more glaring in a Original Recipe 90210/Dawson's Creek kind of way than it was for JT/BB/BU. (ETA: I actually just looked up Nic Robuck's--James--age, too; he's only a year younger than LP.)