ESP: No one asked I just found this relevant. 

Alfred: Hey Mattie!

Matthew: *Looks over*

Alfred: Even if you're older I grew up faster! SO HA!

Announcer Lady Voice: Canada could not grow as fast as America and he was not able to mature at the same time as his brother, causing him to stay as a chibi while America began to become a teenager. Ironically Canada is the more mature of the two.