Why are Jethro’s parents worried about him?

Jethro's parents worry about the burdens and problems Jethro has had to face at such a young age.... as he quickly had to grow into a man. He is reserved and sullen, and yet, he is only thirteen. When his mother talks to him about his lack of interest in the lesson he used to enjoy, Jethro responds, "Seem sometimes that the old lessons are bein' lost in the worry of new things happenin' each day, Ma." From this, we can infer that his responsibilities on the farm are his main focus.