Who teaches you to walk? Who teaches you to speak? It is your parents who teach you to do these basic things in your life. So don't you think that parents are the best teachers!
Firstly, parents know us very much. Parents give us life, and I think that we will spend large amount of time with them. So they know our merit and demerit in details. Meanwhile, they will help us to get rid of our demerit.
Furthermore, parents possessed many experiences. Since they are older than us, they have experienced many things. Sometimes, they are just like our models. And as the saying goes: "Example is better than precept." So we will unconsciously copy some of our parents' habits and styles of behavior, i.e. we can learn many things from them.
Finally, parents will teach us everything. Since schoolteachers can just teach us knowledge from the books, our parents can teach us everything. For example, I learn knitting, cooking and make-up from my mother, while learn fixing leaky faucet from my father. They are the persons who love me most, so they will teach me everything without reservations.
Just as the saying goes: "There is no place like home." And I think there is no teacher like our parents. They are the best teachers in our life.