My New Neighbor?

Man oh man, today I had a visitor
This person has nothing to do with my family whatsoever
My family has only 4 members
Me, my parents and my brother
Perhaps nature thinks 5 would be a good number
Tat’z why this person is sent to act as an equalizer

This new member is a bit shorter
Have a serious face but is actually a JOKER
Behaves like Bart Simpson except without the peanut butter fingers
This person even shared my dinner
All of a sudden, I couldn’t remember
Is this person a visitor or my new neighbour
Hahaha...bet y'all are wondering who's the mischief-maker?