Here is proof, for Jaycoby's future wife, that he is capable of changing a diaper. If he can do it at the age of five, he can do it when he has children of his own.
He is always so helpful and patient with his baby sister. She is never going to have to worry about anyone messing with her. "Bro bro" (what he calls himself when he talks to Ella) is always going to be watching out for his "little goo-goo-ga-ga" (not sure how that nickname stuck, but he refers to her as this a lot).