Skills Increasing Unreasonably Fast

My teenager (17 days before young adult) has an art skill of 6? He's literally only just started 2-4 sims days ago? How? That's not normal skill building and same with his 2 other siblings in other skills they've been working on.

Sims is already "too easy" but this is unreasonably too easy and should have normally taken 3x+ the time. Help!