Charles Ellicott Commentary Genesis 47:3

"And Pharaoh said unto his brethren, What is your occupation? And they said unto Pharaoh, Thy servants are shepherds, both we, and our fathers." — Genesis 47:3 (ASV)

Also our fathers. —Joseph had instructed them to add this (Genesis 46:34), because occupations were hereditary among the Egyptians, and thus Pharaoh would conclude that in their case also no change was possible in their mode of life.