Kenan and Kel/WMG

Kenan's father is really the Diamond Bandit.
Maybe the look alike is just a scapegoat. Therefore, Kel is right and Kenan is wrong.

Kenan and Kel are one and the same person.
The latter represents on how the former wants to formulate schemes.
 * Which would explain why you never see Kel's parents.

Kenan and Kel are Ryan Howard and Jimmy Rollins (respectively).
Notice the resemblances.

Kyra was put in boarding school after season 2.
It would explain why she rarely appeared during seasons 3 & 4.

The fat lady in "Natural Born Kenan" knew the other Rockmores are Asians and was just teasing Kenan.
She did come off as sarcastic when Kenan brought up the idea that he might be switched at birth.

The "real bear" in Montana was really Kenan's mom.
She came up with the same idea as Kenan to scare Roger into quitting his job - and got her hands on a better bear costume.