For The Sims 2 Double Deluxe on the PC, a GameFAQs Answers question titled My teen just aged from a teen to an adult and it automatically changed his.
OMGGGG!!!!!! i found out why. apparently if they are babies u can't change their age. but i tried it on a nanny and i turned her into a CHILD! then back to an elder.
First you press CTRL SHIFT C to open the cheat box..then you type testingcheatsenabled true..click your sim while pressing SHIFT and press.