"The" talk

Mommy: “The baby’s in there” (pointing to tummy)
Joseph: “Oh, is you tummy going to get bigger and bigger and then the baby comes out?”
Mommy: “Yes, that’s right”
Joseph: “Oh, and is Daddy’s tummy getting bigger and bigger?”
Mommy: “No, only mommies can have babies growing in their tummies, not daddies.”
Joseph: (totally seriously, very confused) “I think that’s not right.”
Mommy: “No, Daddy doesn’t have a baby growing in his tummy.”
Joseph: “You’re kidding me” (starts to laugh)