I mean, all the kids grew up on the show but the new Quintin was so much older - not just the actor but the character! If he was 8 when they started, he'd only be 12 at the end yet he was driving and dating.

Libby and Patrick got older but not accelerated like that!

YES. I said the same thing at the time, when the show was airing.

It made no sense because Grace already had an older son named Matthew, who we rarely saw. If they wanted an older character, they should have just used that son instead of quickly aging a different son.

Of course, the reason Original!Quinton left is because coked-up Brett had flashed her boobs at him, and his parents didn't approve of that kind of behavior. So maybe the production team felt an older boy would be safer.