Reaching twelve years of age was a major milestone in a child's life, whether they were Terran or aborigine. Twelve years old was the age in which most children had entered puberty, or the developmental stage.
In Xeno, this meant their bodies would also be able to handle more aether. For elementalists, this meant even more. This was why Alterra's military department started a new program to train these children well in a well-balanced environment.
At twelve years old, children would be taken part in the age group wherein they'd be battling lower-level monsters and finally begin leveling up more.
It was not to say they hadn't been levelling up, of course. After all, a lot of them had been fighting even before they entered Alterra. However, their levels would be limited to about level 5 or 6 before that.
If they went past that, according to the Golds, there was a tendency for the child to fall ill often. If they leveled up too quickly, it could even lead to death.
