What incident shows that Roger is still affected and still held by the learned rules of society?

Two older boys, Roger and Maurice, come out of the forest for a swim and, expressing their superiority over the littluns, begin to kick down the sand castles on the shore. Maurice, remembering that his mother chastised him for such behavior, feels guilty when he gets sand in Percival's eye. While this conflict unfolds, Henry-a littlun who is related to the boy who disappeared-is preoccupied by some small creatures on the beach, which he finds fascinating. Roger picks up a stone to throw at Henry but deliberately misses him when he throws it, recalling the taboos of earlier life.