New Borns

A woman is in the hospital and just had twins, a boy and a girl. But no one is there with her except her brother.
The nurse comes into the room after the delivery and says,”your brother has taken the liberty to name the children.”
The new mother says,”Oh no. he probably gave them stupid names.”
The nurse says,”The girls name is denise.”
The mother says,”That’s not bad, i like it. And the boys?”
The nurse says,”The boys name is De-nephew.”