The school rumors might be vague to the old patriarch, but just how big can the social circles of high society be? They're limited, and since the rumors about her origins had spread from them, tracing the source of these rumors was extremely simple.
The only people who knew the details of her family background were the Gu Family. All that the old man was doing was trying to protect his granddaughter.
The first person to call her was Nalan Xue, who had found out who started the rumors about her. It was a group of idle, gossiping young ladies, and their leader happened to have the same surname as her, a girl named Gu Lili.