The family's hobby is apple growing? That's not right. The fact that it is the boy holding the apples represents something else.
They don't tell us that the boy likes eating apples either.
The correct answer is that it tells us that the family has a fruitful future. The apples tell us that the family hoped to grow in the future. The boy is the eldest son. He would become the head of the family on his father's death and would inherit the family wealth.