This sounds like a mod concept in the making, perhaps some special children who, as you said, age outside of the normal growth window, which can be gifted in any area, once you adopt them and promise to help them grow to their potential.

As for explaining the sudden growth stop (imagine you would need one for when they become an advlt), introduce some sort of magical element, with appropriate theory, to account for this.

Thus began the adventures of DovaKid. Definitely a spin-off just waiting to happen.

QUOTE: Will they add a "smack" dialogue option? Lol

Smack as in 'kiss'? Or smack as in 'apply kinetic energy to seat of pants'?

Haha actually I was half joking. But discipline in skyrim?

I plan on using my master fear spell on my kids if they disobey.