Family either creates a human being. Or, a combination of psychological problems.
In that sentence, Leo Tolstoy highlights the importance of family to create a healthy lifestyle for kids. Because, the parents are the ones who create the conditions for their children. They might not be responsible for the society that surrounds their children. But, they have the biggest role in creating a healthy conditions within their house. Which is believed to be the biggest factor for forming their child's personality.
We can sit together and list many factors that would play a role in creating a child's personality. But, there is no effect that can come close to what the child experience within his household. Let's dive a little deep into this.
Sometimes, I like to work with metaphors. Let's take a ship's captain for example. The captain of the ship might go through high tides, winds and different things that nature would put in his way of reaching his destination. From his experience and knowledge he will know how to deal with these, and will take a decision to change his course or continue in the same direction. It is like, he is using all of these as an add-on to his compass to make a decision of the next move. I think it is fair to say that, the family will create the compass for their kid that he will refer to when he is dealing with different situations in life.