HOLY SHIT FANDOM, WHAT IF THE KID'S CHILDHOOD SHIRT SYMBOLS WERE FORESHADOWING THEIR MATURE PERSONALITIES?!!?!?!?!!
John wore a spade, kismesisittude, it would explain John's crab in the bucket attitude right now. He'll be even more vicious in battle than he already was when he first entered the game. That is my predicition, maybe the John<3<Karkat ship will set sail again since John's new personality will most likely clash with Karkat's. Who knows.
Dave wore a heart, matespritship, he cares about his friends and family. He was the only one of the kids to actually speak well of his guardian-Bro-from the very beginning where as the others spoke of their guardians with an annoyed tone. I'm not saying that Dave didn't have his moments where he thought Bro was annoying, but he still thought Bro Strider was the coolest thing since sliced bread. Even though he wears a poker face, hides behind a cool facade, Dave is the sweetest boy ever.
I believe that Jade wore a clove and that Rose wore a diamond. I am not sure though. But if they did that would explain Jade's peace making personality and Rose's desire to give people "feeling jams".