All Chao have their own personality. For a long time, understanding how Chao personality was decided and what it affected was very speculative. As time goes on we get closer to fully understanding the behaviour and effects of Chao personality.
Sonic Adventure (Dreamcast)
Your Chao’s personality is linked to your Chao’s face. This is determined when the egg is created (and not able to be changed via hatching method, which was a popular theory in the past).
The original game contains three different personality traits your Chao can have:
Each trait can be low, medium, or high. The variations of these traits results in 27 different combinations and therefore 27 different faces. The full list of the faces and personality combinations can be seen on the Chao Gallery.
Kindness does not appear to effect anything in-garden. In Chao Races, it affects the way it pushes the Ball.
Aggressiveness affects how quickly the emotions Anger and Fear drop. A low aggressiveness reduces Anger faster, while a high Aggressiveness reduces Fear faster.
Curiosity effects how quickly the emotion Sorrow drops. A high Curiosity reduces Sorrow faster.
When you breed Chao in Sonic Adventure for Dreamcast, the egg is like a brand new Chao with no link to its previous personality (and therefore face). However, there is a small chance of the child being a copy of the parent who was in mating season (still under research).
Sonic Adventure 2 (Dreamcast)
All Modern Sonic Adventure games
When you visit the Health Center, the Chao Doctor can tell you your Chao has one of the following personalities:
- Big eater
- Easily bored
- Cry baby
- No personality