Thirteen was a big year, becoming a teen. Taking the first true step towards not being a child and working towards an adult. One gains Hight and depth, the capabilities to function increases and ultimately one starts to get glimpses of becoming an adult.
Tiffaney had a long way to go before she arrived at that point a full year, as today was her twelfth birthday. It didn't feel like her birthday because two days ago was a full battery test to get all her parameters, it started with standard knowledge, became PE before cleaning up for lunch, ending with a grueling interview test with the lord of Dyne herself.