'Steven's Birthday' gave great insight into how gems grow - or don't. It also taught viewers that it's okay if you don't grow at the same rate as your peers - either physically or in maturity. Much of the fandom was shocked to find out Steven was 14, as was Connie. That's because he LOOKS her age, 12, which is entirely intentional. He seemed to have a growth spurt at a young age and now he's stopped. Sure, someday he'll probably grow up, just like in 'So Many Birthdays'. But it'll happen when he's ready, and the same applies to regular humans. Check out the A.V. Club's great review of the episode at the link below!