How are the mother, Basset and Uncle Oscar possibly to blame for Paul's death?
Paul's mother is partly responsible for the boy's death because he loves her and is anxious to please her and particularly to get her to love him (although the author states that she cannot truly love her son). He knows that she wants money, and when he wins some money for her she wants more and more. Basset is partly responsible for Paul's death because he gets him interested in horse racing and goes into partnership with him. (Paul needs adult help because he is too young to place bets himself.) Uncle Oscar is partly responsible because he encourages Paul's interest in horse racing and because he begins to make money off Paul's paranormal ability to pick winners. Nobody blames Paul's mother or Basset or Uncle Oscar, but they may blame themselves for the boy's death.