Jim Butcher once said ' when everything goes to hell, the people who stand by you without flinching -- they are your family .' there are many instances where you can see that family is not always blood. Your sorrow, happiness, misery, agony --they share with you. They accept you for who you are; moral, immoral, good, bad, right, wrong etcetera etcetera do not matter to them.
Qin family and Xin family were knitted together despite the fact that there was no blood relation between them, but they stick together in joy and sorrows. When Zhenyi's mother died, Ming Jia stepped forward and did everything in her power to provide motherly love to Zhenyi. And that was the reason she was the most respected woman in Zhenyi's life.