On Mon, 1 Dec 1997, Lord Archive wrote:

"You didn't even train your son in the ways of the quiet thief," grandma
Saotome said while she shook her head. She looked at Ranma and said "My
family is suppose to be trained in the art swindling others out of money.
To rob potential suitors of all their worth before settling down."
... 
"How about the practice of the noisy thief?" asked grandpa Saotome.
... 
Ranma shook his head no and thought, "My grandparents are thieves! What
kind of family do I have."

Uh, why would he shake his head no?  He learned them.