(In the car today on the way home from Indiana...)
my son: "I have part of nana and granda because I have their pants."

me: "What?"

my son: "You have their pants and I have your pants so I have a part of nana and granda in me, too."

me: "Pants?"

my son: "Yea, not real pants. Not the kind you wear. The kind that are inside of you."

me: "Do you mean genes?"

my son: "Yea, jeans are pants."