I'm assuming that you're going by the release years for these character ages (the first game is 1997, the second game is 2001, etc.). Why then, may I ask, are the characters two years older in Island Xtreme Stunts, which was released in 2002? On second thought, more importantly, why are Mama and Papa Brickolini six years older? Did Papa Brickolini cook a pizza so hot it ripped open a tear in the fabric of reality, warping the passage of space and time on LEGO Island, with its epicenter located in the brick oven at Brickolini's Pizzeria?
Ah, yes, Papa Brickolini's (in)famous jalapeno red pepper anchovies double-garlic sizzling tongue-melting new white-hot OGEL special reality-breaking pizza!