"Your grandparents were an old couple. Their only daughter was your mother," Yue Tingfeng said after a contemplative pause, "If we use your mother's age as a baseline, they had her… when they were about 65. There's no way that they would have been able to have a child at that age."
Yan Qingsi's eyes widened slightly. "So you're saying that my mother… was not their flesh and blood."
Yue Tingfeng nodded his head. "That's right. I've been investigating what happened to your mother all this while, but I could only investigate up to the point where your mother came into the care of that old couple when she was about five or six. Any earlier than that though, and I can't find anything. I wanted to clear up everything before letting you know."
Yan Qingsi bit her lip. She was not that surprised when Yue Tingfeng told her this.